In Linux we typically use the "package manager" to install tested and trusted apps from the "repository."
If you like the command line you can simply:
sudo apt-get update
sudo apt-get install bless
Or if you prefer a GUI interface, you can install Bless with a couple of mouse clicks in the Ubuntu Software Center.
(Note: if you still get "many dependencies missing" when installing using the package manager, then there may be a problem with your software sources... we will cross that bridge when we get to it.)