When you start FinalSun, you should see a drag box beside the words "Terrain/Ground:" (underneath the scrollbar near the bottom) and inside that drag box there should be something like 0010 [Cliff Set]. Click on that and you should see a large amount of individual cliff pieces that you can place. For more detail, there is also 0015 [Cliff/Water Pieces], [0019 Bridges], 0025 [Slope set Pieces], 0030 [Waterfalls], and 0049 [Waterfalls-B], among others. If you see a piece you like, simply click on that piece and place wherever you want. It is recommended that you get an add on called "Marble Madness", which will help you place cliffs without errors.
See here:
http://www.tiberiumweb.com/forums/index.php?showtopic=277 for a cliffmaking tutorial
and here:
http://www.cncden.com/ts_downloads/marble.zip for Marble Madness, if you don't already have it.
This post has been edited by BlackieChan: Apr 21 2008, 11:49 AM