In the past, whenever someone has wanted to have a new play-by-post game forum created, it has been very much a manual process that requires members to send an admin (me) an email and then I have to go create the forum by hand. No more. We now have a new automated method, so if you're interested in creating a play-by-post forum, read on.
Step 1. Create a new social group with the name of the play-by-post campaign and be sure to put it in the Play by Post category. This will be the name that shows up in the forums, so set it according to what you want to be shown there. In your social group, be sure to write up a brief description of your game, so that people who may be interested in playing can get the gist of your game from the group description. Key things to put in would be the system used, and a very brief description of where and when the game is set.
Step 2. If you are not a Community Supporter, your next step will be to send me a PM with the name of the group you just created and a request to have a play-by-post forum added. I will then create a new forum for you -- trust me, this is a much easier and quick process for me than it was before.
If, however, you do have a Community Supporter account, you can create your own forum automatically by going into your new group page. At the bottom of the page, in the group navigation bar, you will see an option for "Create Forum". Click that link and your forum will be created and added to the Play-by-Post area.
Notes: Unfortunately, you cannot use the "Discussions" feature of social groups at the moment for you play-by-post. Or, at least, you can't use the integrated dice roller with Discussions, so you probably will want a forum. You can also set your group up so that you must be a member to read the play-by-post. You can do this by setting your group options to be moderated or invite-only.
I will be converting existing play-by-post forums over to the social group method eventually. If you are a current play-by-post GM and want your group moved sooner rather than later so that you can take advantage of the other social group features, send me a PM and I will try to move your group over as soon as possible.
Enjoy! If you have questions about the new process, feel free to send me a private message.