I'm new-ish to the Creation Kit, and I can't really figure out how spells work.

Does anyone know of a good CK tutorial on how to create custom spells? Not just tweaking numbers, but new spells built from the ground up including custom special effects and sounds.

My end goal is to determine how to (if it is even possible) create spells that are scripted to function differently based on other spells you cast. Something like a spell combo where if you cast the right sequence of spells, the final spell has an altered spell effect.