Can't seem to open port 80 or 8080

I just aquired a Mac Mini running OS X 10.5.8. I am attempting to set up an application server running Glassfish. I've been searching the web for valid instructions on how to open up port 80; or any other port for that matter.

Does anyone have any idea how to do this?

Open the port on what? If you mean the Mac Mini - cmd-space -> type in system preferences -> Sharing -> Enable web sharing - that will open port 80. That being said - I would expect the glassfish application to open that port for you.

Thank you for the reply IvanLasston. My goal is to run Glassfish configured to use port 80. While the built-in Apache Web Server opens and uses port 80 just fine, other applications such as Glassfish are denied permission. The GUI does not seem to provide a way to give Glassfish permission to use port 80. There must be a way to open the port for Glassfish, but I cannot seem to find any examples...at least that actually work.

Is there anyone out there that runs Glassfish (or even Tomcat) on OS X 10.5?

Do you have the application firewall on? System Preferences -> Security -> Firewall
That would be the only default thing that would block glassfish. Do you have any 3rd party firewall or 3rd party anti-virus running?