Start by checking your connection string - this may help: Simple SQL Connection String Creation
When you have that, things should be smoother.
But ... two things.
1) Never hardcode connection strings - they change, particularly when you release software. They should be stored in a config file of some sort - the way I do it is like this: Instance Storage - A Simple Way to Share Configuration Data among Applications
] - it's probably overkill for your app, but ...
2) Don't use Attach to connect a DB - create and populate the DB in SQL via SSMS. Attaching is a special debug mode of Sql Server that is only available in Express versions, and is not going to work in production. If you want to use an Access DB directly, then don't use SQL Server at all - use the Ace DB engine, and access the file via Odbc instead.