Neebie with immobiliser issues

Hi guys
Firstly sorry my first post is an issue..thats how I found the forum!!
Ive have bought a freelander thats been sitting around for a while.
Its a 1998 1.8 petrol. The immobiliser seems tempermental along with the central locking. I think its all out of sync. Not sure.
Firstly which is which button on the fob?
Is there a correct procedure for dis-arming the immobiliser?
Im assuming when I open the door that the immobiliser should be off?
It isn't?
how do I disarm. press a button or hold the fob by the key? 2 button Fob BTW

Thanks in advance!!

Push one button to lock and alarm/immobilise it.
Push the other button once to unlock the drivers door and deactivate the alarm/immobiliser, push it again to unlock the other doors. If you hold the unlock button in it lowers the tailgate window.
If you are having problems change the battery in the key fob and resynchronise it.