i see on other webcomics, there are links to their forums and to pages with a list of their characters. How do i do that?

Well, first you must create your forum. It's an option available to you in "My Controls". Select the comic you want the forum for and choose the "forum/blog" tab. Click "Create New" and you now have a forum!

Linking readers to your forum is a bit more tricky since you must edit your template to provide a link to your forum. But it will help you to use this DD code in your template:

<!--[FORUM_URL]-->
-This prints out the URL of your forum if you have it enabled. If you use this you must use it inside a link: <a href="<!--[FORUM_URL]-->">Forum</a>

This requires that you know how to do HTML! If you don't I just suggest you stick the link in your signature or frequently tell your readers about your forum in your Author's Comments.

Link to your Cast page? It's done in about the same manner, but you must simply create your own cast page in HTML format and upload it to your comic account in the Files tab.