Also, while in the game there are rectangular tiles and on the map in the editor there are rectangular tiles that correspond as far as ground texture, the elevation on the map indicates the elevation of corners between tiles in the game. For example, a road will have a row of tiles one square wide in the game and for textures, but the elevation needs to be the same two points wide for the road to be flat - if you change the elevation in a square that appears to be next to the road, you may actually tilt the road up in the air. Conversely, a ditch that appears to be one square wide on the map will be two squares wide as far as textures go, because it is the point between two squares that is low. In the Desert deciduous trees become palms and evergreen trees become shrubs. The map display always shows springlike colors and the same two kinds of trees.
Bridges can be difficult to place so that they come out well.
There is a limit to how big a forest section can be - not very big on the lowest zoom setting. If you want a lot of forest, I would recommend creating all the sections you think you will need in advance - then place them where you want them without creating new ones that might make old ones disappear. Note also that forests on hills may sometimes appear to be floating in the air at a distance since they appear out of the background before the hills do in some cases. If you're having trouble placing rivers and roads, review the instructions and hints on the top half of page 66 of the manual. This places a binoculars unit on the map that can have different skill levels.