Reading books on line would be a help. See the bold bit below.

In SQL Server Management Studio Object Explorer, connect to an instance of the Microsoft SQL Server Database Engine and then expand that instance.

Right-click Databases, point to Tasks, and then click Attach. The Attach Databases dialog box appears.

To specify the database to be attached, click Add, and in the Locate Database Files dialog box, select the disk drive where the database resides and expand the directory tree to find and select the .mdf file of the database; for example:

C:\Program Files\Microsoft SQL Server\MSSQL.1\MSSQL\DATA\AdventureWorks_Data.mdf

Important:

This example assumes that the AdventureWorks database has previously been detached. For information on detaching a database, see How to: Detach a Database (SQL Server Management Studio).

Optionally, to specify a different name for the database to attach as, enter the name in the Attach as column of the Attach Databases dialog box.

Optionally, change the owner of the database by selecting a different entry in the Owner column.

When you are ready to attach the database, click OK.