How I add my money off my Apple ID to my Apple Pay?

You cannot transfer money out of your Apple ID Account balance. It is only for purchases.

tomorris112 wrote:

If I owe Apple Pay will they take it out the Apple ID?

Here is what you can use your Apple account balance for:

What you can buy with your Apple Gift Card or Apple Account balance - Apple Support

It cannot be used for purchases made using Apple Pay.