have rootkit

hey guys, man, my head is spinning off of my shoulders..!! I googled rootkit a couple hours ago, and knew I had to get here fast. but after reading so much HERE, I have no idea where to start. I know what an illegal copy of windows is, and what porn is. but keyloggers, crack, etc, no freakin clue.
maybe a month ago I noticed mcafee taking forever to finish a scan, would say scanning rootkit. happened again today. I searched my computer for rootkit, it took forever, didn't find it. so I googled it.
got this laptop about 6 months ago. its all legit. Walmart hp special with windows 8 or 8.1. its the only one we've got, and a few of us use it. no business use. but if I can ward off any damage from a rootkit, im all ears. where do I start.?
thanks for any help guys, john