Installing a Single CD Player

I've bought a VW single cd player and wanted to know how i go about installing it myself as i've never done this before.
currently ive got the radio in one slot, a tray type thing for tapes above and the heat control belowe it, is it simply a case of pulling out the top tray, connecting the cd plug to the radio and sliding the cd player in above the radio?
is there anything else i need to consider e.g. a code etc (its a gamma radio)