Tunemymac pop ups when turning my mac on. Is it a virus?

It is an ad.

Close all windows and qiit Safari from Safari menu.

If you cannot quit Force Quit Safiri.

Press option + command + esc keys and force quit from the window that opens up.

Hold shift key down and launch Safari.

Antivirus:

http://www.thesafemac.com/mmg-antivirus/

Did you install TuneUpMyMac? If so, you need to uninstall it immediately. It's junk. Not only is the entire genre of "cleaning" apps for the Mac worthless (see The myth of the dirty Mac), but this one in particular is well-known for particularly "scammy" behavior. You can find uninstall directions here:

http://www.tuneupmymac.com/uninstall/

Of course, that's assuming you trust the company or the site:

Note that, if you downloaded this app from some other junk site, like Softonic or Download.com, you will probably have additional crappy adware to remove. See my Adware Removal Guide.

Thanks for the reply. I am on it!