Recording calls

Hi, I´m a Spanish engineer and I´m novice in Asterisk programming. We have to develop a dialplan to record the calls. The calls must be recording at differents files containing the caller ID, the receiver ID, duration, date… My problem becomes with the parked calls. If the parking extension is 700 and the parkings positions 701-720, over what extension I must work? I´ve obtained the CallerIDNum, that shares with the user that brings the call, but I don´t know where I have to start Monitor and where stop it, as well as how to return to the previous recording inf the parked time expires. Thanks you.