How can I find viruses and damage done to my computer and remove them?

I got a few viruses on my computer. I obviously picked up the viruses from the internet. How can I find and remove them? My antivirus was turned off while I was surfing the web without me realizing. My computer is expensive enough and getting a virus on it doesn't help. Besides, I don't want my personal information to be viewed by other people(even though they probably have already).