In the entity properties, there is an option to flag a certain entity as an objective. Normally this is a ZONE or an item that needs to be picked up or an enemy that needs to be killed. FPSC doesn't need to be told WHEN the objectives are completed, it just needs to know what entity ARE objectives, then when all the objectives in the level are complete, the level will end on it's own.
Remember that each individual objective needs to have its own objective number. If you give two entities the same objective number thent he player will need to only complete one of them in order to get through the level.
The one and only,