How do you actually install expansion packs? [SOLVED]

I think the problem I'm having is actually getting the expansion packs to instal onto my computer? When putting in the serial code it wont let me press continue. Is there a way to get expansion packs onto your computer differently?

//EDIT

Never mind I've done it.


Moderator edit: OK, good to hear that! Problem solved, topic closed.

- Carlos G.