What should I do if my iMac shows virus alerts?

I accidentally added an extra letter when typing in a website. McAfee popped up (I HAD UNINSTALLED IT ABOUT 2 YEARS AGO) and wanted to run a scan saying I had 5 viruses and to click on checkcapde.com to fix the problem. I have never checked to see what the name of the security system is on my computer but when I looked it had checkcapde listed. Question. Is this the security system I am supposed to have?

[Re-Titled by Moderator]