Automatically Fill Registration Forms
When creating an account on a new web site, you can use 1Password to fill in all your registration details. You can also use 1Password to fill your credit card information.
Automatically Enter Personal Details
Before it is able to fill your information automatically, 1Password needs you to define one or more Identities. You can create these in the main 1Password application by clicking the Add Identity toolbar item:

Clicking Add Identity will bring up the Identity Details window where you can fill in all your information:

You can add as many identities as you want, such as a Work identity, a Personal identity, and even an Alias identity with fake information to provide to sites you do not trust.
Once your identities are created, 1Password can use them in your web browser to fill registration forms, shipping address forms, and even weblog comment fields. Select Fill with Identity from the 1Password toolbar icon menu and select the identity you wish to use:

Automatically Enter Credit Card Details
You can automatically enter credit card information in much the same way as Identities are used to fill personal information. For credit cards, add a new Wallet Item:

There are many Wallet Item types in 1Password. In this case, select the Credit Card type:

The Wallet Details window will appear, in which you can enter all your information for this new credit card. Just like identities, you can add as many credit cards as you want.
Once your credit cards are added, you can automatically fill online payment forms and other forms requiring credit card information by selecting Fill with Wallet from the 1Password menu:
