Don't understand your question? So I'll assume you're asking is BO2 good to play on the PC? I like it a hell of a lot better than Ghosts and I enjoyed BO2 quite a bit...most folks would LOVE Ghosts if it was on par with BO2.
but how do you play do you have to buy it or do you have to go on something
Neither BO2 or Ghosts are free, so unless there's a 'Free to Play Weekend' then yes you have to purchase these games for the PC, but you can rent them for the Consoles (Xbox & PlayStation).
When I got Bo2 for PC, I didnt want to go back and play Xbox.
Its so much better because you have a mouse and keyboard!! get it!!