I'd like to, when i click in "save" to change the content, i message would appear in somewhere the admin page that the saving was successfull, there is some way to do that?
I'm afraid not, unless you don't mind digging in PHP files to add this.

Please see viewtopic.php?f=4&t=7789&p=12639 for a related discussion.
Would a button such as those at http://lab.hakim.se/ladda/ be sufficient for you in communicating the same thing?