More info? What step are you stuck on? Downloading, installing, opening, using?
I probably won't be able to help as I'm not good with macs, but if your problem is using it I may be able to help.
Like "onlyleftname" said, I think you can just download the optimal solution solver, here: http://kociemba.org/download.htm It is on the third box of text.
P.S. You have no idea, how much I wanted to link you to the OAQT and call you a noob. (;