First, make sure you have the latest Alliance.
http://www.sourceforge.net/projects/alliancep2p
If you do not ... uninstall your current alliance.
If in Windows... delete the Alliance folder in Program Files after uninstalling.
If in Lin/Mac... delete the entire folder you were storing alliance in.
DO NOT SKIP THE FOLDER DELETION STEP.
Now if you haven't already, install the latest Alliance.
When you open alliance -- go to View, then Options.
You should see the port alliance is using.
Open that port in your firewall. Forward that port in your router if you have one (
http://www.portforward.com ... or check your router's documentation).
Then PM me for an access code.