Depends on two things, if they are already in game or if they are arriving later.. Sounds like you have them arriving later
If they are arriving later you will have to use the (has-arrived-delay) from the (objectives) list, in the sexp instead of leaving the field (true)
(event)...... You can name your event
(when).........this just reflects when the event takes place
(true)..........change this to (has-arrived-delay)
(0)...............zero will beam free opon arrival
(ship name)......... name of the ship to free beams
do nothing)........you already have this (beam-free-all)
Also try opening a mission made by someone in fred2, this can be a lot of help to learn the use of sexps..
Hope this helps

Oh, welcome to HLP
