hello all....totally new here...hoping yall can help my confusion!

i've had a mc303 for some time now but barely know how to use it....i also have the Cakewalk software for my pc...

my plans were to use them both together to make tracks of electronic music....however i learned quickly that having the usb>MIDI cable wasn't enough and that apparently the groovebox needs a MIDI controller regardless of the keys it already has on it

so now i'm in the market to get a keyboard

so what am i looking for as far as being able to do this??? would the minimum requirements simply be a keyboard that is a "MIDI controller"???

also....any advice you can give me on using cakewalk with the mc303??

thanks much all!