You can't make new tables, just use the ones that are there already
Actually you can. I just learned how to do it yesterday on my Mac using the instructions below (plus you need to setup port forwarding/mapping on your computer's network router, if you have one). The new table would actually be running on your computer, so you'd need to keep it running and have an Internet connection or the table would go away. If you want to check it out, there is now an additional table that I created on the default GCCG server labeled "GCCG League".
See this section of the GCCG manual:
3.2.1. Setting up an additional table(S)
Install binary package (or source and compile it) for your platform to have program called ccg_server.
Then install the game module, the server module and the game specific server module
./gccg_package i game server game-server
Launch your server for p players and connect it to the meta server meta
./Server --server meta --bet bet --players p game
Without --server argument, the game server registers itself to the default meta server. Default bet is $1 and default number of players is one.
Don't forget to open appropriate incoming TCP/IP ports at your firewall if blocked by default.
If you wish set up more than one table, you need to give different port numbers for each server using argument --port num. See following table for port numbers.