Thanks a lot clovis.
package not installed (I really don't know why), but I'm happy that finally I learned a little about terminal!
but I've a question : if the command was dpkg for installing them, so what was apt-get ???
and why these files are not graphically installable (like windows)??? isn't that more user friendlier??? (I'm new to ubuntu (4 months), and I have this problem with that to)