How can i play a computer game meant for pc on my mac PLEASE HELP?

Unfortunately the likelihood is that you will have to buy them in mac version

Run Windows on the Mac through virtualization software. You will need the free release candidate of Windows 7 and the activation code or any other Windows CD you've got lying around. Performance may not be as good as natively on a PC.

You can use a software called vmware fusion.It allows you to run windows operating systems(OS) inside the mac.I doute you'll want it tho because it cost money.You can always find other programs that do the same functions but are free.I know one called Virtual box but i'm not sure it it works on macs. Here are your options 1:Buy the mac version of the game 2:Use a virtual pc software (more info in first paragraph)

If you still have your old Windows installation disk and a valid CD-Key, you can install Windows on your Mac and use any Windows software. You can install it through Bootcamp (Free), VM Ware Fusion (Not free), Parallels (Once again not free), Virtualbox (Free), etc.

You would have to buy the mac verison or install windows on your mac. There is also using "Crossover Games" to mimic windows library to run windows program, but it does not work on all programs. I would suggest you check out their list of tested programed to see if your games are supported.