'Adventures of Caelereth' is a free play by post fantasy RPG taking place in the world of Caelereth, of which the United Kingdoms of Santharia is a huge part of. You can read more background information at the main site, the Santharian Dream. Santharia/Caelereth is a very huge fantasy project in the style of J.R.R. Tolkien and always welcomes new players at the RPG message board. If you'd also like to help out with developing the lands, be sure to check out the main site and the Development Board and read more instructions there.
By the way, just to give you a start with navigating through the Forum: The menus to the left and right can be hidden or shown by clicking on the claw graphics on top of the Forum (the left claw deals with the left menu, the right claw operates the right one). The left menu contains links to various information regarding the RPG, including how to create characters, as well as some useful tools, while the right menu has a search function as well as a list of recent posts.