A good general rule is never to use waypoints to make things happen. In Cadet mode it ties down the player to much and it means that in Veteran mode your mission won't work at all, because the player will miss one or all of the waypoints since he doesn't know where they are. Waypoints should only be used to provide
additional (i.e. not essential) information for people playing in Cadet mode. That's all assuming that the player is the group leader of course. Use a marker (preferably linked to text in the briefing) to show the player where the secluded spot is. This spot should not be too far from the town, long journeys are a bit dull.
Right, now to answer the question
I think what you mean is that for the mission to end the player must have been in the town, the town must be clear of the enemy, and the player must now be in the secluded spot.
You need three triggers. Two over the town and one in the woods.
Trigger 1
area - over the town (drawn quite widely)
condition - player present (see below)
on activation - townVisit=true
Trigger 2
area - over the town
condition - enemy not present
on activation - hint "The town is clear"; townClear=true; "1" objstatus "done"
Trigger 3
area - over the secluded spot
type - End#1
condition - player present (see below). You also need to put the following in the condition line near the bottom
this and townVisit and townClear
For the player present condition you need to link the trigger to the player. Click on Groups (F2) and draw a pale blue line between the trigger and the player, just as if you were grouping them or using synchro. You will then get special options in the present/not present/detected bit. Choose whichever is best.
And that's it!
Trigger 1 simply checks that the player has been to the town. You may want to miss this Trigger out, it's not adding much and if for some reason the player doesn't fire it then he will have trouble making the mission end. If you keep it in make it clear in the Briefing that the player must lead his troops into the town.
Trigger 2 checks if the town is clear and when it is it tells you and marks the objective with a green tick.
Trigger 3 will not fire unless the other two have already fired. townVisit and townClear are variables which tell Trigger 3 that Triggers 1 and 2 respectively have been fired.
There are several good tutorials in the Editors Depot which cover triggers, and in fact the one included with the game covers some of this kind of stuff. Start/Programs/Codemasters/OFP/Readme. Watch out for the typo, at one point it says "sy" when it means "v1".
Hope that does the trick.
This is a pretty bare bones approach. For instance you can use something a bit classier than a hint to indicate that the town is clear. But I'll leave that to your imagination.