Creating my own plugin

Our cms uses fckeditor. One of the missing possibilities is to create an internal link to other pages of a website. For that reason I want to develop a plugin that can do that. I read the instructions at http://docs.fckeditor.net/FCKeditor_2.x ... Script_API, but I don't understand it. I used google to find a tutorial or better instruction, but no success

Can anyone describe how to create a custom plugin?