Does someone has a examplesketch for something like this?
You are asking for someone else to write a sketch that is very specific to your hardware setup. It is unlikely that anyone else has used the same hardware for the same thing that you want.
You need to break your problem up into smaller pieces.
The shield link you provided is not in English, so, unfortunately, most of us can't read it. It does not even have a picture of the shield, so I can't even guess what a nodo shield does. Apparently, you know, and it works for you.
The link on the shield page, to a pdf file, is blocked by my company. I have no idea why, but it prevents me from seeing if there will be a pin conflict with the nodo shield and the ethernet shield.
Presuming that there are not, the sketch that you have now must read from a remote, determine what action to perform (button 5 was pushed, so ...) and perform that action (send a message).
Your ethernet shield, as a web server, could serve up a page that looked like your remote, with buttons on it. The page itself would contain a form, and each button would be a submit button.
When a connection is made, you need to parse the GET command, and determine whether it is an initial request, or a result of a submit. If it is an initial request, serve up the page. If it is a submit action, determine, from the data in the GET request, which button was pressed, and perform the same action that was performed when the button on the remote was pressed.
Posting the code that you have now would be useful. We could suggest how to modify it to also be a web server.