Add User to SQL Server 2008

Open Microsoft SQL Server Management Studio.
Right Click the server of choice in the tree and click Properties.
Click Security.
Make sure the SQL Server and Windows Authentication radio button is selected.
Click OK.
In the tree, expand the Security folder under your chosen server.
Right click Logins and choose New Login.
Enter login name.
Click SQL Server Authentication radio button.
Enter password.
It may be necessary to unclick User must change password at next login if not using Windows Server 2003.
Click Server Roles in left menu.
Click all entries.
Click OK.

In the tree inside your instance, expand the database folder, then Security.
Right click on Users and click New User.
Enter the User name and login name.
Enter the default schema.
Under Owned Schemas click all checkboxes except "guest".
Under Role Members click all checkboxes.
Push OK.

To test:
Click the Connect button at the top of the tree.
Choose Database Engine.
Enter login name and password and click Connect.