I have no idea how many times it's been updated since release, but I'm currently using RPG Maker 2003 1.10a. I also have RPG Maker 2000, so if the process is different for that edition, please let met know.
Also, my apologies if this question has been asked before, but the new site search doesn't seem to let me search per forum board, so I couldn't check if a topic like this already exists.