AvalonEdit
Sample Application

In the SharpDevelop source code download, you will find a small sample application in SharpDevelop\samples\AvalonEdit.Sample.

The Code Project article

There is a Code Project article based on the sample application: http://www.codeproject.com/KB/edit/AvalonEdit.aspx

However, most of the material from that article has been included in this help file.