I tried using the minor spell sequencer during a battle but nothing happened? I know I should have access to some lower level spells when casting this, but where do I find them--and furthermore, how do I use them?

Sequencers and triggers work like this; you cast the spell BEFORE the battle and set which spells you want to go off when you use the trigger. You press okay, and a little icon appears in your innate abilities menu. When you use this, and target whatever you want, the spells you selected in the sequencer menu will be cast at once, instantaniously, i.e. with no cast time.

These are good because you can memorize spells to put into your sequencer/trigger, then cast the sequencer, put the spells in, then replace them with other spells. effectively:

Minor sequencer - 2 spells of up to 2nd level
Sequencer - 3 spells of up to 4th
Trigger - 3 spells of up to 6th