I'm trying to create a Killing Floor map and i have the latest Unreal Engine but i dont know how to export my map to Killing Floor. Where can i find the correct version of Unreal Editor ? How can i export my map with current version ?
Killing Floor was created with the Unreal-2 engine, not the Unreal-3 engine (UDK), so you're kind of trying to export backwards. You're going to run into problems doing this - if it even works at all.
Try copying it across in chunks. First select all the BSP (Right click on a BSP mesh and go Select All > Same Class), then copy and see if it will paste into the Unreal-2 editor. As BSP should more or less be the same in both engines, this should work. As for meshes and other assets, you'll have to export them from your Unreal-3 package, then import them individually into your assets package in Unreal-2. ... And then manually place them back in to your map. This is generally the only way you could do something like this.
What you're trying to do is very arduous and tedious due to the fact you're trying to move a map from one engine to another. There is definitely no in-built function in UDK for backwards-exporting. I wish you the best of luck if you're still attempting this.