Your friend must have iMessage turned on in the Message app's settings. That should be enough for him to receive messages using his phone number. To receive messages from an email address he must add that email address to the Receive At list; also in the Message app's settings.
To receive a message on the iPad you must do the same thing, minus the phone number, of course.
You really should start a new thread in the appropriate area, instead of asking your question in an unrelated thread. If you go and post an introduction in the New Member Introduction area a moderator will be along shortly, and supply you with some useful links. Or you can just read the other introductions and get them there, if you would rather not introduce your self yet.
Welcome to the forum.
