iNeed some help with my iMac

hi guys im new to Mac's and this forum, i got a chunky iMac from a friend without a mouse and keyboard and i was wondering if i needed a mac mouse and keyboard because my microsoft keyboard doesnt work all that much, by that i mean it can type but thats it nothing else and my mouse just refuses to work with it
i hope you guys will be able to help me out
thank you
D3VJ1