Is there such a software that lets me hide and lock images and other stuff on my desktop?

Right click the desktop and select "New Folder". Right click the new folder and select "Properties". Study the menu you get to see what your options are. One of them is "Hidden". But I suggest you go one step farther and put your hidden folder on a thumbdrive so you can lock it in a box.

You can't click on a hidden folder, you have to type the path into your program.

Every program you use has a menu at the top of the screen, although it might take some clicking to find it. You should study that menu and all its sub-menus. You don't need to memorize everything, just remember that it's there. The desktop has the menu in an icon named "Start". When you have done all that, then you can claim to know how to operate a computer at the beginner level.

Just for one example, you might prefer to rotate your monitor for looking at images in portrait format. Most video cards have an option to rotate the screen image for that purpose. That is in the menu you get when you right click the desk top.