Before you start, make sure that you have installed the original The Sims 2 game on your computer.
To install any extension pack for The Sims 2, you simply have to insert the extension disk in the CD/DVD ( make sure you have a serial number before you start; it usually comes with the disk ) and the autorun window will pop up. From here you should simply follow the steps provided.
If you need further support, I suggest you use Google.