I need to generate this .rpm file with alien to .deb and then i need to sudo dpkg -i the.deb file
But in terminal it does not show me it has converted it.
Im sure its a small command that im not aware of please enlighten me
First, you should use Alien as a last resort, you are better off compiling from source.
Second, your command is off, you have two -- in front of the .rpm, use
sudo alien your.rpm
See https://help.ubuntu.com/community/RPM/AlienHowto for details