How do I remove Win Antivirus 2011?

I've already tried 'press WinKey+r, type command etc...' That doesn't work, I can't use a blank CD to save stuff on, I can't download any REAL free antivirus scanners... What do I do?! Please give me easy instructions, I'm only 14 and don't know computers really well... please I seriously need help, I don't want my dad to have to spend $100 to get it fixed at Best Buy...