The proper command is
apt-get instead of
You need to be careful when typing commands, as you can do lots of damage. For example, typing
mkfs.ext3 /dev/sda instead of
mkfs.ext3 /dev/sdb will destroy all data on that drive.
THe command's proper form is:
sudo apt-get install mysql-workbench
The above command fetches mysql workbench from the official Ubuntu repository. A repository is a web server containing many programs or files.
It seems like you already downloaded the
.deb file associated with the mysql-workbench package, so you can just install it by
cd /path/where/you/downloaded/file/ and then running command:
sudo dpkg -i mysql-workbench-community-6.0.9-1ubu1204-i386.deb
EDIT: If you have dependency problems, you should try
sudo apt-get -f install