We do not provide ISBNs unless you are working with Artmobile.
Artmobile provides you with an ISBN and retail website to sell your book from, with an option to sell on Amazon too. More info here!
If you are not working with Artmobile, you would need to purchase an ISBN from www.Bowker.com. If you give us the ISBN and retail price, we can create and place the bar code on your back cover for you (that charge is $25.00).