So you want to install mono on Debian/Ubuntu?
But doing all the steps on your own is hard?
Just run the scripts and everything will be done for you!
./install-mono.sh
./install-monodevelop.sh
./install-path.sh
The first script installs mono, the second one monodevelop and the third one installs the path variables to .bashrc so you can access the newesst mono and monodevelop from the command line.
If you are on a server, you probably don't want to install monodevelop, so leave the command just out.
Remember, that this will let you access the newest from the terminal, not command run (like ALT+F2).
You have to open the command line and uses the mono or monodevelop commands.