If you're looking to just send the viewer to a link in the same page/thread and you're doing it in BBCode, you can use the link/anchor codes. A link is what they click to get there, and the anchor is where they end up once the link is clicked.
So in your TOC for a game info thread, you do the following:
and in the post for the character sheet you put:
Bear in mind these can, but don't usually use actual URLs for the posts. This makes it possible so you can put them in the middle of particularly long posts if you want to point to a specific section of the post, etc. You can see how they're used in this thread
As for actual links to other pages/posts that are outside of the 24 posts you can currently view in the thread, I don't know.