A thought has puzzled me for a long time, Did God create the earth or just the "Garden of Eden"?

It's a parable...
In an age when few people could read, and most of the listeners were young, because people didn't live very long, parables... stories were told to explain and make moral points and such.
The bible is well worth reading. You must seperate the childish parables from the accumulated wisdom contained in the bible.

Actually god created only one human who is much more higher than you who is Prophet Adam. God pitied of him being alone in heaven so God took on of his rib while he was sleeping and created a woman and her name is Siti Hawa. Then one day, Prophet Adam and Siti Hawa was taking a stroll in heaven and they saw a tree. The tree the saw was full of fruits. Then the devil started to tell lies to both of them. He said that if they eat the fruit, the will become an angel a they will never die. Siti Hawa was amazed of what the devil said so he persuade Prophet Adam to eat the fruit with her. Then, Prophet Adam remembered that God told the not to eat fruits on one of the tree so he told Siti Hawa to not eat. Siti Hawa continued to persuade Prophet Adam to eat the fruit so finally Prophet Adam and Siti Hawa ate the fruit. I'm not so sure what happened after they eat the fruit. I can only tell tell that they begged God to forgive their sins.God forgive their sins but with one condition which is they have to leave heaven. Prophet Adam and Siti Hawa agreed so God threw them to earth. They were threwn separately. After 40 years then they met each and other. Siti Hawa gave birth to a few children after being with Prophet Adam for a few years on earth. Prophet Adam made his male children marry his female children. When Prophet Adam got grandchildren, he made the same thing to them. The generation goes on until now.
*As you may know Prophet Adam is the father of all kinds of humans

Billions of people have read or heard what the Bible says about the beginning of the universe. The 3,500-year-old account starts with the well-known statement: “In the beginning God created the heavens and the earth.”

The Bible account of creation hinges on the fact that there is a Supreme Being, Almighty God, who created all things. Who is he, and what is his nature? The Bible reveals that he is quite different from the deities found in popular culture and mainstream religion. He is the Creator of all things, but most people know very little about him.

After creating in the heavens things both invisible and visible, the Creator and his firstborn Son focused on the earth. Where did it come from? The variety of chemical elements making up our planet could have been produced directly by God’s transforming unlimited dynamic energy into matter, which physicists today say is feasible. Or, as many scientists believe, the earth could have been formed out of matter ejected from the explosion of a supernova. Then again, who is to say whether there might have been a combination of methods, those just mentioned and others that scientists have not yet unraveled? Whatever the mechanism, the Creator is the dynamic Source of the elements that make up our earth, including all the minerals that are essential for keeping us alive.

The book Nanomedicine states that the human body is made up of 41 chemical elements. These basic elements—carbon, iron, oxygen, and others—are all present in the “dust” of the earth. Thus, as Genesis states, humans truly are formed “out of dust from the ground.”

It was the Creator’s original purpose, and it still is his purpose, that obedient humans enjoy never-aging life, ever overflowing with youthful vigor, free from all boredom, always having a worthy purpose to fulfill, a life of loving and being loved in a true, unselfish way, perfectly—in a paradise!—Genesis 2:8;

The answer is found in the bible. If you allow yourself to be reasonable the bible's explanation below will give you the answer not other people's ideas.
The Genesis account opens with the simple, powerful statement: “In the beginning God created the heavens and the earth.” (Genesis 1:1)
Genesis 2:5-8 " No bush of the field was yet on the earth and no vegetation of the field had begun sprouting, because Jehovah God had not made it rain on the earth and there was no man to cultivate the ground. 6 But a mist would go up from the earth, and it watered the entire surface of the ground.
And Jehovah God went on to form the man out of dust from the ground and to blow into his nostrils the breath of life, and the man became a living person.  Further, Jehovah God planted a garden in Eʹden, toward the east; and there he put the man whom he had formed.
In previous chapters, the first two humans were not like animals. Instead, they were created completely human. Their original home, Eden, was “a paradise of pleasure.” (Genesis 2:8, Douay Version) They were “to cultivate it and to take care of it.” (Genesis 2:15) Additionally, their role on earth included this very human administrative assignment: “Be fruitful and become many and fill the earth and subdue it.” (Genesis 1:28) As their offspring increased, they would have the task of extending the boundaries of this beautiful garden, transforming the whole earth into a paradise. The Bible consistently notes that the earth will remain “to time indefinite, or forever.” (Psalm 104:5; Ecclesiastes 1:4) So the Paradise earth was meant to serve permanently as a delightful home for perfect humans, who would live there forever.—Isaiah 45:11, 12, 18.
Adam and Eve were created perfect, and the instruction for them ‘to multiply and fill the earth’ would necessarily require that their offspring marry one another and reproduce. (Gen. 1:28) Such a union would not be incest. This objection reflects knowledge of the risk to children when brothers and sisters marry in our day. These are frequently born with some physical deformity or mental incapacity. The reason most lands today have laws forbidding marriage between close fleshly relatives.
But as perfect humans, Adam and Eve and their children would have been perfect as were their parents.
For more information on this subject, please go to jw.org "Online Library" for free downloads, publications or read online.

God created the entire earth first. Genesis 1:9/10 God said. "Let the waters under the heavens be collected together into one place, and let the dry land appear." And it was so. God called the dry land "Earth."
After God created all the living creatures then in Genesis 2:7 God created the man. Genesis 2:8 says, "Further more, God planted a garden in E'den."
So this explains that God first prepare the earth , created all the creatures and then form the man. He took the man and placed him in the beautiful Garden of E'den .
So to answer your question God bought the earth into existence first and then he prepared a little part of the earth as a paradise and called it the Garden of E'den, in which he placed the first man Adam.