This is my first tutorial, so it will be quite brief and easy. This will possibly be the easiest but most fun, effective thing to add to your game.
First, start by creating a new Common Event in the Database. Call the new common event "Learn [Spell Name]" Now, go to page 3 of the selectable Event Commands, and select "Change Skill" Now, select the skill that you want to use. You can even use a custom skill. After that is completed, go to the "Items" tab. Create another item. Now, name this "[Spell Name] Scroll", or something that matches it. Then, create a description saying "Teaches the player the [Spell Name] Spell. Now select the "common event" pull down menu, and select the common event that we just created. Give your item some unique features (A sound effect, icon, price, etc.) The sound effect I used was number 18, which is Teleport01.
I'm sorry I can't provide any screen shots, I recently uninstalled my photo editing software by accident, and when I try to install it, it gives me an error. I will post screen shots as soon as possible.
EDIT: Did I post this in the wrong section? Sorry if I did.