How to close ports...

Hi, Using SuSE 7.0 with Suse Firewall. should like to close some ports like port 12345,12346 etc... How to set this in the SuSE Firewall (I use Yast 1 to configure...) and how to test? In windows I had an option in IE to block a sender.How to do this in SuSE?Both konqueror and Netscape... Yhanks Jean-Paul faessen