How do you add spells from a trigger to a spell book?

How do you add spells from a trigger to a spell book?

How do you add spells from a trigger to a spell book? I really need help with this so if you know how please help me out!!

Well you could have multiple spell book spells and then have triggers take one away and then add a different one but that could mean a lot of custom spells.

Edit:If you mean adding a spell that runs on triggers to a spellbook, just stick the spell in and it should work fine.