i was learning about using Visual Web Developer to create new database, when i click in the Database Explorer to expand Database diagrams, I get the Message: 'This database does not have a valid dbo user or you do not have permissions to impersonate the dbo user, so database diagramming is not available. Do you want to make yourself the dbo of this database in order to usee database siagramming?'. When I click Yes, I get the message 'This database does not have a valid dbo user or you do not have permissions to impersonate the dbo user, so database diagramming is not available. Ensure the dbo account is valid and you have impersonate permission on the dbo account.' And this only offers me an 'OK' button to click on.

somne one suggested to dl the SQL server management studio express and change the ownership of the database to sa. but i couldnt find where to change the ownership.
anyone can give a detailed description of where i can actually find the ownership in the properties? please explain by using the exact labels in the program. Thank you very much for the help!!