[lowfighter]

Creating a template:

Suppose it's a template containing one airfield. Open one of the empty maps in map builder mode. Delete everything except say one airfield on the empty map. Modify the remaining airfield as you wish. Save. Exit il2. Go to root/maps/empty1a (Ithink that's the name of one empty map) and you'll find an actors.static file. For easier reference later rename let's say airfieldstemplateactors.static. So then whenever you buid on a map you can paste this airfieldstemplateactors.static on your map.
You can think of an airfieldstemplateactors.static which contains a lot of different airfield types. Then when you build your map, paste airfieldstemplateactors.static inside, then copy the different airfields and paste them to your desired locations on the real map.

The town template:

First decide which city texture you want to use. Go on empty map and paint that texture. Notice the texture is repeating. Open the empty map in FMB map mode delete everything and place the buildings on the city texture you painted on the map. Make sure you place buildings such that you fill a WHOLE repeating city pattern. Save. Go out and save the actors.static maybe like city_nameof citytexture_actors.static.

EDIT: you can use the city_nameof citytexture_actors.static whenever nameofcitytexture.tga is present on your map. The buildings will not match the texture when you try to paste on a different texture. For example you build your template on "midcity.tga" texture. You can't use the template to paste over a "centercity.tga" texture (if that's present on the map).

There are also some other ways...