Some Question for modding TOW2-3

[Sneaksie]

You can edit a map using dedicated Map Editor (Builder.exe). Open any map, save it with different name and alter as you want, then choose it in Mission Editor.

Here's the old German guide for Editor. MP mission creation changed since then, but some of the info is still useful.

I suggest modifying an existing MP scenario for starters. Change forces, their placement, you can also choose another map.