Help with custom background.

So I have decided to dive into the world of D&D now and I'm just creating my first character. I then decided to make a custom background for my character or more like customize an existing one, my question is what do I write on the character sheet? I've picked the Charlatan background and it has the most skills and proficiencies to fit the background I have for my character, allthough it needs a bit of tweaking and the "lore" of it is wrong.