This is just a mod to add the continent of Yastreovakia into Crusader Kings 2. Valsora is the map used by The East Pacific region in NationStates. If you aren't a member of TEP, you likely won't get much use from it.
To install the mod, simply download the files, the unzip them using 7Zip, or a similar program. Once unzipped, move them to the mods folder of the CK2 directory.
Unfortunately, I don't know how to adjust the territories, religions, etc, so for now you will have to use Shattered World to make the map more tolerable, unless you want it to cultures and religions to look like a Jackson Pollock painting.