Virus Cleaner How Do I Use Avast Virus Or Worm Cleaner?

How do i use avast virus or worm cleaner? - virus cleaner

I downloaded avast virus cleaner and when I opened it, I need to enter an administrator password, my desktop does not show the image is blue and I can not resolve this problem, I use avast and it does not change, and have a Dell Dimension 4550 and has tried a system restore with Ctrl + F11 and nothing happens, please help me