Configuring customer portal can be somewhat confusing the first time around.  Here are a few basic guidelines to get you going in the right direction:

• For each object that you expose in a portal, the sharing model must be private (unless you want to expose all records of that object to your portal).
• Use sharing rules to recreate the sharing model for All Internal Users.
  Example rule creation for accounts:
  
• In order to expose an object and/or tab to the customer portal the following must be true:
  • The tab in question must be supported by the customer portal.  From the article “Why can’t I see my tab in the Customer Portal?”:
    

    Even though all objects are displayed in the Customer Portal setup, only the following can display as tabs in your Customer Portal:
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    Custom objects

  • When exposing a custom object, make sure to check ‘Available for Customer Portal’ on the object properties:
    
  • Ensure that the customer portal profile(s) have access to the object:

    • Object Tab Setting: Default On

    • Standard Object Permissions: Object Read (minimum)

    • Field-level security on the object

  • Make sure profile(s) are assigned the correct page layout

  • Create the customer portal:

    • Ensure ‘Login Enabled’ is checked

    • Click Customize Portal Tabs (top) and choose tabs to expose (all of the above must be configured before tabs are exposed)
      

    • Click Edit Profiles button (bottom) and assign profile(s) access to login to the portal
      

  • Add/verify portal management buttons on the account and contact page layouts
    

Self-registration will allow existing contacts within your Salesforce org to sign up for portal access.    To enable:

• Enable self-registration on the portal itself
• Give contacts ability to self-register
  • The field ‘Allow Customer Portal Self-Registration’ determines if a contact can self-register.  By default, this field is not checked.  First, enable visibility:
    • Grant the Visible permission to ‘Allow Customer Portal Self-Registration’ for portal administration profiles
      
    • Add the ‘Allow Customer Portal Self-Registration’ field to the appropriate contact page layouts
  • Update all contacts to grant self-registration capability (this can now be accomplished through data loader as well)
• Contacts should now be able to self-register through the portal login page
  • Note:  The email address provided on the self-registration page must match the email address on the contact record exactly (it IS case sensitive!).