Try this link http://portforward.com/routers.htm
find the model of your router and then click on it on that page and you will get a list of different applications that require port forwarding.
If you can't find the application you're looking for then just choose a common application like limewire and use it as a general guide. (some details may differ with using the actual application and accessing its' preferences but the guide on how to port forward generally fits all applications.
Hope this helps =]