To use .mdf file, you need "Microsoft SQL Server Management Studio Express", it is a free tool, to modify, show ... mdf file.
Here a link to download the microsoft tools. (You can change for your native language).http://www.microsoft.com/downloads/details.aspx?displaylang=fr&FamilyID=C243A5AE-4BD1-4E3D-94B8-5A0F62BF7796
Remarque: to open SQL file, generaly you need to have a login and a password. by default the login is : sa
and no password (the field password must be empty).