If you're new and looking for some tutorials and ways to get better using the tool, try the Tutorial in the Help Center!
The Help center is the application containing all the documentation. The Help Center comes standard with Arbortext Editor (starting with 5.4 F000). You can launch the Help Center directly from inside Arbortext Editor, or separately by going to the Start Menu->PTC->Help Center in Windows.
The tutorial can be found under the "Authoring" section of the Table of Contents.