I just got my computer and I know that I have put all kinds of things on it that is not necessary please tell me how I delete these unwanted sites

Well what type of things do you think you don't need ?

You say sites? Are they saved favorites or installed programs

It's commonly called "Crapware". Go to Add/Remove programs and uninstall programs that you don't want. Also, in Internet Explorer, click on Bookmarks, and right-click on the bookmarks you don't want and select "Delete".

Aftewards, download CCleaner and MalwareBytes and run those. In CCleaner run at least two registry scans and delete everything it finds (save backups for a couple of weeks, just in case).

CCleaner - Home
Malwarebytes.org

It depends on the kinds of things which you have put in your systems. If they are installed programs, download and install revo uninstaller and then uninstall all unnecessary programs; you can equally do this by going to add/remove programs from control panel.
If they are just files you no longer need, to delete them completely, press shift + delete key

To remove unwanted programs with Windows Vista go to Start, Control Panel, Programs and Features.

To remove unwanted programs with an earlier version of Windows, go to Start, Control Panel, Add or Remove Programs.

To remove unwanted websites under Internet Explorer, go to Favorites, Organize Favorites.

Yes I agree just go to (no pun intended) remove in control panel and get rid of what you don't want.

The may I suggest download Advanced Windows Cleaner from IO bit and once installed will clean all traces away so you'll never knew they were there. And it's FREE.
Note; after use stop program completely as uses a lot of memory.