Below is a link to some good instructions...but once again, we need more information about your computer, specifically the operating system:
How To Shut Down Unnecessary Start Up Programs
In fact, the link below provides a number of Newbie TIPS. Click on the link, then spend some time exploring the tips provided there:
A Few 'Tips' For Computer Newbies
HOpe this helps.
How do I remove items no longer needed or wanted