To get your unique free OpenID from your existing yahoo account should not be a difficulty. After 5 reasons why you need to use OpenID, I found some user have difficulty to get their own OpenID in their yahoo account. Here is the solution for you. Just follow the step to step instruction as stated below.
1. Log in your yahoo email account.
2. Select "Options". Note: it should be found at the top right of your window.
3. Select "Mail Option". Note: You will be altered to a new page.
4. Select "Accounts" which is listed out at left side of the window.
5. Select "Add or edit an account" at the right column. Note: You will be altered to another new page.
6. Select "Account information". Note: You will be altered to another new page. In this page, you are required to enter your yahoo password again to verify yourself.
7. After verification is successful, select "Manage/Create your OpenID" in the "Sign-In and Security" column. Note: You will be altered to another new page again.
8. After that, select "Show Customisation Options" which can be found in the lower part of the window.
Or, you can just go to http://openid.yahoo.com/ to skips several steps above after sign in your Yahoo account.