In the first part(link here), we show you how to write a simple extension for AFS, and compile it in C++ environment. In this part, we will continue to interpret the usage of the compiled extension in Async Flash Studio.
Now we have got a dynamic linked library "Extension.ext", just copy the file into the "extensions" directory of AFS, typically

"C:\Program Files\aSyncRIA\Async Flash Studio\extensions\"

Launch AFS, create a new project with the main swf set to the built swf in the first part. click "Add" button in Extension panel, you can see the "Extension" item in the list of available extensions on the "Add Extension" dialog.

Add the extension to your AFS project, either embed or not. If you select not to embed the extension file, you should copy the file into extensions directory in order to run the final execution program successfully.
Now click build->generate menu, and then run the generated program, you can test the extension now.