Hello terrainer! As some of you may know, theres already a few terrain tutorials, but I thought I'd post my version here. I hope you find it useful I belive that the terrain is one of the key aspects of a map, and It is THE most viewed part of a map, and you want people to enjoy what they are looking at if they have to look at it for an hour or so. As a first, and what I find to be a VERY useful tip in the World Editor, is that while you are placing down doodads, holding down shift while doing so allows you to stack certain doodads. Also, you can click on a doodad, then hold Ctrl and the left mouse button, then move the mouse to rotate doodads. Another important tip, is to use the Raise and Lower tools under the Terrain Pallete. Having a flat terrain is boring. However, be careful to not overuse these tools, unless you are trying to give your terrain a jagged look.
Here, I will explain how to do a waterfall. But first, if you know how to import things to your map, there is a great waterfall model here http://wc3sear.ch/index.php?p=Models&ID=580&sid=. I wont be using this model for my demonstration however. To start making your waterfall, (make sure that you aren't building it on a hill that you've created, as this can cause some very odd water effects) create a realatively large cliff area using the Raise Two tool under the Terrain Palette.
You can leave some areas untouched by this tool as you see above, so the water doesn't look so flat and boring. Next, use the Decrease One tool on the second layer from the bottom on the front like this.
Make sure that the waterfall dooodads line up with the edge of the cliff. Now simply repeat the process on every level of the cliffs, making sure that waterfalls below match up with the waterfalls above them. A good tip is to use smaller and smaller waterfall doodads as you move down the cliff.
Putting the rocks in spaces between the waterfalls is a good way to start placing the rocks. Next, you can begin to place cattails, lily pads and shrubs around. Remember, cattails grow on the edge of the water and in it. You can place the shrubs in some bare spots, and on the rocks.
Now, to finish off your waterfall, use the Raise and Lower tool in some of the shallow water areas, and placing some rocky looking textures in the water, and if you want to, find some cool statues to place by the waterfall.