Just want to know how to a trigger

What do i exactly doso that it only creates a unit for a player that is currently playing, say like at the start of an rpg map where you can pick from different units, i want it only to create a chgooser unit for those players who are playing.

Pick every player in (All Players) and do (if (((picked player) slot status) equal to is playing) then do (unit- create one <unit> for (picked player) at (<region>) facing default building degrees) else do (do nothing)

thats an if/then/else inside of a player group-pick every player and do action

hope this helps