Hi spaced, well if you look at the engine you should be able to figure out which belt is driving the a/c pump, the pump has pipes etc.. attached and connects to the small radiator in front of the main radiator, on most cars the a./c pump has an electric clutch on the front so that the inner part does not turn when the a/c is off and does turn when the a/c is on, check this out first, if it is turning then the a/c should get cold.
If it turns but does not get cold then follow the a/c pipes around the engine compartment, somewhere is usually a small gadget in a pipe with a glass window in it which allow you to see the gas/liquid passing (or at least bubbles in the liquid gas), find this and clean the glass so that you can see inside. Run the engine with the a/c off and watch the glass and then get somebody to switch on the a/c, you should be able to see the gas/liquid start to flow if the pump is working OK.