set up database in sql server

I want to add a new database to an existing sql server 2008 r2 instance. I then
want to write report builder 3.0 reports to access the database by using a
shared datasource.

My problem is I setup the database using ssis 2008 r2 manager and let the
database be created with all the defaults. Now when I write a report builder
3.0, the data source does not know who I am. The database only knows me as the
dbo. It will not let me add and/or change any user roles.

Thus can you tell me how to setup a new database with the appropriate
persmissions so a report builder 3.0 report will know who I am?

New database is created from model database, you can create necessary users/permissions in model database before creating new database

Hope this will help