first: It is a good idea to tell more about "how" to install the tool. A simple "Drag" and usage like "<cc1:RichTextEditor ..." isnt it.
Either you add a "<%@ Register Assembly="RichTextEditor" Namespace="AjaxControls" TagPrefix="cc1" %>" on top of your markup page, or (better):
add in Web.Config like "<add tagPrefix="rte" namespace="AjaxControls" assembly="RichTextEditor"/>" in section pages | control.
But, may be, you think about all USers of the tool are profi enough to do it by themself :-)
Okay. Much more important:
==> How can i get access to the content of the rte? I await properties like "HtmlText" or something like that to have access to that content.
==> I implement a button to test the rte. But in the click-event i did not see the text input made before. How can i get access to the current content?