Create a new BDC application

1. c heck the server service to make sure the BDC service is started; other you need to create a new BDC service application.

 

2.When you create the BDC service application, make sure the application pool account must have admin group.

      3. When add connection in SP designer, your windows account must have access to your external database. It is used to create a connection. Otherwise you will get access is denied by BDC. Later you need to tweak you BDC model manually to set the SQL credential. Otherwise  you will get “NT authority/net work is denied”. The original BDC try to use iusernet account to access to the database.

   4. Go to CA and click Service Connections Manage form the ribbon for the application,

 

 

http://blogs.interfacett.com/creating-a-custom-content-type-in-sharepoint-2010-by-spike-xavier

to change the content type group of a list, check this  item, click edit property on the ribbon and change the content type in the interface.