The mechanisms are relatively simple to figure out but almost impossible to describe ...
Best option is to remove the doorcard and have a look.
You haven't said what year/model you have ?
This is for the S3, 2/300tdi and TD5
The cards are held in place with plastic clips, you have to remove the window winder, door handle and lock escutchion first and then wiggle it about and it will come off.
You will likely break some of the plastic clips.
You can get replacements on eBay (etc). There are different tuypes, get the card off and then order the bits to put it back on.
If the card hasn't been off before there is a plastic bag/seal that needs removing before you can get to the workings.
Once the card is off you can see exactly whats going on ....