I searched the web but can't find a simple example for sending strings to a server red5 RTMP, using an as3 (flash ide-compiled).
where can I find a tutorial about this?
Your question is fairly broad, but I can direct you to an old blog post of mine that gives examples of how to send AS3 Vectors. This may help you with how to perform communication with the server. http://blog.infrared5.com/2011/08/red5-vector-support/