Go to Bowker's My Identifier Web page (see Resources). Select "ISBN Numbers" from the menu under the login prompt. Click the tab labeled "Single ISBN Number" (unless you want to purchase a bar code, as well).
Select "Buy now." If you don't have an account, you will need to set one up at this point. Click "Create an account" and fill out the form for your profile. Select "I accept--create my account" at the bottom of the form.
Log in with your email and password if your are prompted to do so. Select "Shopping cart" in the menu at the very top of the page, then click "Continue."
Fill out your billing info, or click "Same as contact info" and select "Continue."
Pay for your order. All credit cards are accepted.
Add your title information, publishing status and price information. Title information will include your book title, publisher and author. An ISBN number will now be assigned to you, and you will be able to enter your listing within the website for free.