Help understanding respec

Hi,

I'm new to the game after playing Baldurs Gate and I'm just getting the hang of things.

I used to gift bags thing to get the respec mirror at fort joy as I always mess stuff up.

I've played around with it a little but I'm a bit stuck. I had lohse as a wizard and red prince as a knight but I have now redone them to have red prince as the wizard and lohse as a metamorph (first time I want to try different things even if it's harder 😂)

The issue I have is that despite putting points in the relevant places they both have no skills relating to that now.

Is this how it works and I need to find skill books for those classes now before they can do anything?

Thanks for any info/advice!