why can't i log in to the server i can log into the forum but when i try to log onto the game it will not let me i do not understand

read the sticky's in "the den general discussion" section on the forum

Read stickys; Sticky; FAQ - Signups/connection etc howto

You have registered on site Kp's Network MMO Project ?
If you havent, you have to have an account there in order to login to game.
Then you have to have your realmlist set up correctly, for eg, here is more information about the Den;
Wiki, Den Info

Recommending to use the "KP's Loader" instead of modifying the "realmlist.wtf" file.

But if you insist to modify the file, here is some small guide I found;
Modifying realmlist.wtf

- Saz