System Generator: How to configure the pins for the signals of your design?
Do you have a '.ucf' (= user constraints file) as part of your project? Pin assignments are defined there. Something like

NET "some_net" LOC="F3";


means that the net "some_net" is connected to pin "F3". You can change these entries so that nets connect to other pins, though you must be careful. If you're targeting a particular board, every pin will be connected to something, and you don't want to cause contention (by assigning a 0/ground/low to a pin that's connected to 5 V, for example). Also, there are banking rules that you must adhere to, etc.