You can place a trigger and a gamelogic.
Make sure your editor is in advanced mode.
Give your playerunit a name.
Now the trigger: The trigger borders should be covering the whole map (or the whole area where every enemy has to be killed) Set it to "east" (if east is the enemy you have to take out) and to "not present". Set type to "end 1"
Fill into the condition line:
this AND (extractionpoint distance
nameofyourplayerunit <= 15)
You can adjust the "15" if you want the end being activated at a greater or smaller distance from the extraction point.
Finally you need to place a gamelogic at your extraction point and name it "extraction point".
Thats it.
Make sure the player knows where the extraction point is! For example by placing a viewable marker at the extraction point.
You can also use any unit or vehicle instead of the gamelogic for extraction point. Just make sure it is named "extractionpoint". (For example you could use a jeep or car)
If you want a red flare when the player killed all enemies and is getting near the extraction point, making it easier to find the exact extraction point if the extraction point is a gamelogic:
Place a second trigger anywhere on the map. Again its borders should cover the whole map or the area that shall be without enemies in the end. Again "east", "not present". Dont change the type for this marker this time, it should be "none".
Condition line:
this AND (extractionpoint distance
nameofyourplayerunit <= 70)
On activation line:
myredflare = "FlareRed" camcreate (getpos extractionpoint)
This will spawn a red flare at the extraction point if the player gets within range of 70 meters and all enemies are dead. (you can adjust the 70 to another range if you like, depends on the terrain (when will th player be able to see the flare))
All this should do for singleplayer missions. For multiplayer it gets a bit more complicated because you have to check if all players are near the extraction point. But I suppose you are creating a singleplayer mission?
I strongly advice to go deeper in the tutorials and editors depot (use search engine). It has a side effect: You find so many useful ideas, techniques, scripts and tricks when intentionally looking for other things ;D
Another collection of tutorials that might help:
http://www.geocities.com/opfmapping/Tutorials.htmI advice to download all files in the section "My tutorials", this is a good beginning.
Also make sure you have Mr Murrays' Operation Flashpoint Editing V 2.0 (editors depot) and a OFP commands manual, both are VERY useful and a must in my opinion.
cu slowworm