Pressurisation
CS-TMX, Pressurisation of the aircraft pressure hull allows an artificial cabin altitude to be maintained when in flight. Simply, all that beaut conditioned air which is directed into the aircraft is allowed to discharge at a predetermined rate. Because there is a limit to the pressure to which the aircraft can be pressurised, let's say 9.4 psi or thereabouts, the aircraft (such as the L1011) is able to maintain a sea level cabin altitude up to around FL220. This means that at FL220 the cabin will be pressurised to around 9.4psi differential. That is, 9.4psi higher pressure than the ambient temperature in which the aircraft is operating. If the FltAlt was left set at FL220 the cabin would begin to climb as the aircraft climbed above that level because it will only maintain that same pressure differential. If it tries to "over pressurise", the cabin controller should not allow it to do so, but in the event that it does the "safety Valve" would open to relieve the pressure and so prevent airframe damage. It is too many years since I was operating on the L1011 to be specific, but lets say that the FltAlt side of the scale says 22000 and opposite is says ) for the CabinAlt, if you were to set 22000 before take off, the cabin would maintain your departure field elevation initially. If that were sea level, you would maintain that up to FL220. If your departure airfield was, say, 2500' AMSL, then as you climbed toward FL220 the cabin altitude would slowly descend to sea level. It is important that as descent is started the cabin controller is set to the destination airfield elevation to arrive on ground at that airfield with zero cabin differential pressure.
As far as the rate of change of cabin altitude is concerned, this "rate" is set on the same controller on which you select your FltAlt. I am impressed that as a Flight Attendant you are keen enough to want to know more about the control of the environment in which you work. My advice would be to speak with your friendly F/E next time you go flying and get him/her to show you first hand how it is done.