Learn

Syntax: learn
Syntax: learn <class>

LEARN without an argument tells you the experience needed for all classes,
available for you.

To actually level up, you need to go to a trainer like Lucan or one of the guilds
you can find on HELP KRYNN. You then enter LEARN <class> to advance.

I.e. if you want to level warrior, enter LEARN WAR. As long as you have enough
experience, and you are at a trainer who can help you, you will progress in
that level.