1. Central Admin > Application Management > Create or Extend Web application > Extend an existing Web application
2. Select the web application that you want to extend > Create a new IIS web site > give it a description > use port 80 > enter Host Header (e.g. test1.elcom.com) > leave the security configuration at default values
3. Choose the Zone (e.g. Extranet) > click OK
4. Central Admin > Application Management > Application Security > Authentication providers
5. Click Extranet > Change the Authentication Type to Forms > Check Enable anonymous access
6. Fill in AspNetSqlMembershipProvider as the Membership provider name.
7. Fill in AspNetSqlRoleProvider as the Role Manager name.
8. Leave the Enable Client Integration as No. FBA does not work well with Office integration. It is because FBA relies on cookies and most users disable persistent cookies in the browser, that is the default security settings. So if you want to enable client integration in FBA, you have to enable persistent cookies on each client, if you do not do that, if you try to open a Word document in a FBA web application, you will get the FBA logon screen in Word. So we will almost always select No here. It is just too hard to get integration working with FBA.
9. Click Save > Go to Operation tab > Alternate Access Mappings, you will see that it creates a mapping for extranet