How do you get rid of the ytdownloader virus?

So, I was listening to music on YouTube, and something popped up (I think) saying YT Downloader I DID NOT CLICK IT. But now it keeps showing up when I look it up, it's slowing my computer down, it'll give me random links/pop-ups, etc. Every time I try to undownload it, my Virus Protection will say there was a Trojan that was stopped. I keep trying to add it to my desktop but it won't add, because that way I could shred it. I have a Windows 8 - HP. I just got this computer and my parents will kill me if anything happens. PLEASE PLEASE PLEASE help!