Volkswagen: VW remote key programming, car immobiliser, volkswagon dealers

Question
I have just bought a 2002 VW Sharan 1.9 TDI Sport, it only came with one key fob but I have acquired a spare from another vehicle. I got a new blade cut to match my existing key.
I have been told that there are 2 parts to the remote, one for  the doors and one for the immobiliser. Apparantly I need someone with proper diagnostic equipment to program the remote into the car immobiliser, I presume I can get this done at the VW garage. The other part is to get the remote functions to lock/unlock the car, I believe this should be pretty simple but I've ammassed several different instruction options. In fact one set actually de-programmed our existing remote but did not allow us to program the new one. (We were able to re-pregram the existing fob).
Can you give me the proper instructions?

Answer
firstly, there are literally hundreds of frquencies for the remotes, and it has to be the exact one for the central locking to pick it up. secondly, the only sure way to do it is to programme it using the diagnostic equipement as you tell the central locking there are two fobs, this one and this one then it logs them and remebers them (all other fobs will be deprogramed by this eccept the two that are newly done) the transponder in the key requires volkswagon dealers to obtain a secret code from volkswagon which changes daily. so really it is a main dealer job.