How do I get learn a spell I can use with needing a potion or book or anything. I am missing something.

Spells are learnt from reading Spell Tomes, they go into the books section.

Spelltomes/College in Winterhold teach new spells.

There are levels of spells:
Novice
Apprentice
Adept
Expert
Master

Each level has new spells, and the tomes associated with each level appear after your skill reaches that level.

I am trying to find Colette, and have been roaming around the college and can't find her. does anyone know where she is?

She's there somewhere... if you have it detect life can help you find people a bit quicker.

You can also wait in the proffessor's quarters (forgot what they were called) at night and scan the rooms.. she's there around midnight