CAST

The spell craft skill allows a character to learn and cast spells. The higher this skill, the more effective a spell is and the lower the chance of spell failure.

To cast a spell its CAST 'spell name or number' TARGET 'your name or targets name'
Note, you can learn spell multiple times. The more you learn a spell, the more effective you are with it, the less chance you have of failing in the casting, and the longer it lasts or the more damage it does.