There are plenty of good diagrams on these forums for basic wiring. Its just a matter of searching (maybe the Wiki too?)
But to sum it up... make a ground "chain" that connects all the commons on all sticks and buttons and connect that to the ground of whatever encoder you bought (IPAC, etc).
Then wire each NO (normally open) "tab" on all sticks and buttons directly to the correct input on the encoder (which in most cases is silk screened on the PCB (1UP, P1B1, etc).
I hope you got the wiring kit from DM, since that will save you the headache of compiling the parts you need seperately.
Any other questions, just shout them out.
-Stobe