There are three types of magic: Spells, Rituals, and Spontaneous.
Everything officially called a "Spell" is fully predefined. If you want to use a spell, you need to log into the SM3 website and use the spell parser to cast your spell. You paste the output into your forum post.
If you don't have a spell, and you want to caste magic anyway, you use Spontaneous Magic. Again, use the parser, but tell it you're using spontaneous instead of a spell.
You can trade spell using spell hashes. Other players give you spell hashes for spell they know. Once you enter that hash on the web site, you know that spell, and can use it. (Assuming you have the correct skill levels.) For some spell hashes, see the "Spell Freebies - Aka Basic Grimorie" thread:
http://forum.battlemaster.org/index.php/topic,1477.0.htmlI recommend you read the magic section of the web site:
http://lemuria.org/SM3/welcome/magic
