OK I know this is a dumb question but I've read about how to get spells etc. but exactly how do I actually cast the spell? In most games there is a key assigned or using the right mouse button or something but I can't figure out what I have to do to actually cast a spell in this game.

Would appreciate any help.

The right mouse button casts the selected spell; to change spells I think you drag an active spell to the quickbar then press that number to equip it. You start out with the fireball equipped by default.

Thank you for your help. I now know how to use spells.