We can't supply a connection string, it is pretty much unique to your database (in terms of type, server, default table and security.
This[
^] is the website I use for all things connection string related.
As for creating the unique identifier, you should do this in the database table rather than code if possible. When you define the primary key you should
define it as an identity column[
^].
Once you've inserted the user, the generated key is available by calling the ScopeIdentityMethod():
This[
^] has some good examples.