hello, and a question about getting started

hello. I'm a bit nervous and intimidated using these forums, so I'll post here first.

last night I stupidly clicked on a vague link from someone I trusted and then found that other people said it gave their computers a virus. I use avast's free antivirus, and it didn't alert me to anything at the time, but I did notice some strange behavior pertaining to Java, digital certificates, and then something stopped working and had to quit. I did a scan with avast and looked through the anti-malware programs already on my computer and ran malwarebytes. it didn't find anything. I also had Spyware Doctor on the computer, but it was an old version, so I downloaded the new version and scanned with that. it warned me about a bunch of cookies and some registry keys infected with a trojan. I think this was an old infection from last year that I thought I had gotten rid of. I deleted the cookies through the browsers and am now trying to get rid of the trojan, which brought me here. however, I am confused about how to get started with the README steps--it says to uninstall all other antivirus applications. I did a quick search to see if the free version of Spyware Doctor and avast are the same sort of antivirus and if I need to uninstall one, and which one. avast is the one I've been using, and the free version of Spyware Doctor won't fix the problems that only it discovered. *confused*

thank you for your time and any and all help.