Classes are simply starting templates. They provide you with a set of skills that get
you going for your first few levels of the game. After that you train the skills you
want to gain. You can keep going with your class's theme or switch it up.
Each experience point you gain can be used to train new skills. Each skill costs
1000 experience if it is the same level as you. For every level below yours it
costs 100 experience less, down to a minimum of 100 experience. See help train
for more information about training skills.