So, u have most of the map done so far, but, where are the details too this map? Too add trees, hit the picture that looks like a tree on your toolbar.Then select the tree u like, then click and drag your mouse over the area u want it. Now u have trees. There.
Too add details, go too the object placing button(forgot wat it was called), select the civillian(tech for tech buildings)and u will either see another drop down list or all the tech buildings, in the drop down list(if there is 1)select any kind of thing u wish too add.
Simple, i would tell u how to create custom ai but there already is a tutorial over that.:(