Someone help me with antivirus?

I downloaded a song on mp3 rocket. A red box popped up and said file contains Trojan-downloader.WMA.Wimad.n and said it couldn't be disinfected. I called my brother-in-law and he told me to go to iobit.com and get advanced system care. I downloaded that, scanned and supposedly repaired all my problems. I went back into mp3 rocket and deleted the song. I then clicked delete on the little red box and it said the file could not be deleted- file not found. Do I still have a virus? How do I go about checking to see if my computer still has a virus? Please help me! I have waited years for a computer and my hubby finally bought me one with income taxes! I don't want to screw up my computer. FYI: I installed Defender Pro when I got my computer, so I did have a little defense.