If I remember well, a standard ubuntu installation has by default all ports close. So I believe it is normal that you did not see anything in firestarter - although I do not use it (and thus can't be sure) - unless you have already configured server software in your box.
This snippet will list your iptables rules (the <...> part must be filled by you, its your account name) in a file `ipt-rules' inside your home directory. Attach the file or copy its contents in your message, to figure out where you should put your allow commands.
Tell me also for what protocol(s) you want your ports to be open; there is no need (and is not generally advised) to be open for all.
iptables --list-rules > /home/<account>/ipt-rules
chown <account>:<account> /home/<account>/ipt-rules