You don't need to ask but its always a good idea just to be sure your not starting to map something that anyone else is currently working on. At the mo I don't think anyone is working on much of it.
We have a world which is as yet unnamed tho we had some name ideas for it. One region on the right is called Ansium and that was broken up into many tiles of which they have been taken and regionally mapped to some extent. They are shown in the CWBP wiki on a map and you can click through to more detail on those regions. Within those 30 or so regions are many many places which might have names and no map or as yet unnamed and unmapped. The areas to do are endless. Some of those 30 or so regions are less well mapped and you can if you want take one and add to it. But I think it would be better to do a map of something as yet unmapped rather than rehashing an existing map. Still, it is up to you.
If you look at my sig there is a link to the CWBP place names where we have had people map areas. Its also a good idea to look in the CWBP folder for any posts for a named place to see if its been done. Also, each of the regional tiles have been mapped by someone who has a good idea about whats in there and might know if its been done or where to go to look for previous information.
Basically - its open to everyone and anyone but its better if it all hangs together instead of making maps that pull against what has already been done.
So if your interested in mapping something then pick a place, if its in Ansium region then look at the tiles, then find a named town or think of a place you might want to put into one and post a new thread. We have a naming convention for the threads so look at the existing threads and keep to a similar format. There is a CWBP place scraper that keeps my link list up to date with all the new posts people put in. I also keep a zoomable map of the entire world and I like to keep that up to date with peoples maps all under one roof.
So take a peek at the overview map and the wiki and let us know what you want to do.