Since we installed an antivirus program, my pc is running really slow.
Should I uninstall the program? What other solutions do you suggest?
This is the sort of thing where you look and see what's wrong and find a way to fix it. Every program you use has a tools menu. If you use tools a lot it will be a toolbar across the top of the screen. If you rarely use tools it might be hidden. In Windows you can click "Start" and select "Control Panel" and that gives you a menu of menus to control everything the computer does. You can right click anything and most of the time get a menu for that specific item. For example if you right click the desktop you have the option to rotate the monitor image in some graphic cards. That allows you to have an image that is high instead of wide, by turning your monitor. You don't need to memorize all these things, just be aware that they are in there. Then you can claim to know how to operate a computer at the beginner level.
If you want to use the internet you need to learn how to use the internet. Everybody uses google.com so you may as well use it too, just so everybody doesn't poke fun at you. You can search for "google advanced" to see what else it can do for you. For instance you can search a specific web site; you can search for a specific filetype. You can use images.google.com to search for a picture that looks like one you have. Then there is video.google.com which indexes much more than just youtube.
100 search engines: www.distancedegrees.com/2008/lose-your-wikipedia-crutch-100-places-to-go-for-good-answers-online/
Google tricks: www.johntedesco.net/blog/2012/06/21/how-to-solve-impossible-problems-daniel-russells-awesome-google-search-techniques/
Google advanced: iwastesomuchtime.com/on/?i=20501
You need to do some occasional maintenance on your software. The place to go is tucows.com and search "maintenance" or any subject that interests you. You will definitely want Ccleaner and Spybot.