Boot Camp issues switching between OS's

Hi everyone, my first time asking a question here =]

So i recently got a Macbook from my brother, it was running Mac OS X Snow Lepoard i think, before i go on sorry if i sound stupid in asking this. im quiet confused myself =/ ... Anyways, i took the Mac down to our local Computer fixing shop, and i asked him to change it to Windows 7. he did it all, installed drivers etc. It's Windows 7 Home Premium at the moment. im just curious on how i can go back to Mac, or switch between. I have tried the following -

Hold down ALT while it boots up, all that shows is 1 picture of Windows. i thought their should also be a Mac image to start up to? but it doesn't show.

While in Windows, go down to the side bar and try to Restart it in Mac OS X, nothing happens. Just boots in Windows

I have only 1 Disc which my friend gave me, it says on it Snow Lepoard, and if i click it while on Windows. it says Remote Installer? and there is 3 options to choose from, i tryed to install Mac but its just so weird and i don't get it.

So, the real question is, why doesn't the Mac hardrive show up when im pressing Alt during the start up.

Thanks for any help! =)

~Richard