To get your Steam ID, do the following:
Step 1) If you already have the developers console enabled, go to Step 2)
Go to "My Games" on Steam.
Right click, properties in ZPS.
Click on "Set Launch Options"
Type: -console
Step 2)
Start ZPS. Once you are in a server, bring up the console and type status on it. A series of Names with numbers next to them should appear acording to how many people are in the server. Look for your name. Now, copy the number sequence next to it. That is your steam ID. It should look like : STEAM_0:0:00000000 (Example)