I am not sure I am doing this right but it isn't working. So I open the construction set and go to file, data... I select "Beautiful people" because I want to edit the mystic elf. Character> Race> and then the mystic elf. I gave them the High elf's fortify magicka ability. When I launched the game the mystic elf didn't have this ability. What did I do wrong. And my apologies, I am new to this...

Are you looking for the Ability in an existing character? If so, try making a new character and see if the ability is there.