Edit: Ahh liam, you beat me to it lol
Hello and welcome to the forums cassius_b. We shall help you the best we can
Terrain Creation: These videos may be a little old but they show how to create and edit the terrain. The editor looks a bit different now but it is all roughly the same.
http://www.chi-ad.com/DokuWiki/doku.php/videotutorials:gs_introduction_officialThere are also these tutorials that you can look into:
http://www.forum.aurasoft-skyline.co.uk/viewtopic.php?f=46&t=1107Check out the "Generating Terrain" and "Terrain Edit" videos created by our forums TattieBoJangle
For extra information, the terrain editor can be found as a dockable panel usually hidden on the right hand side of the screen. If you take a look in the bottom right of the skyline editor, you should see some terrain, step along until you find "Terrain Editor".
Select the main directional light in the scene and click the generate terrain button found on that panel.
The subsequent tabs across the top of the panel step along for editing, painting terrain; followed by Vegetation and the road system.
GUI EditorThe GUI Editor is still a WIP and will result in the odd bug. One which has been fixed in the development version where clicking on the render screen while playing the game will result in a crash.
Make sure all the GUI workspaces and files are gone, then load a gui from the "Asset Library/GUI" Folder.
I hope this helps