In dash of Unity, there’s no obvious way to add a new application shortcut in it. Here the solution(from here).

1. Install “alacarte” by running “sudo apt-get install alacarte”;
2. Run “alacarte”, you will see the familar UI where you were creating new shortcut in Ubuntu 10.04;
3. Create the application shortcut as usual;
4. Done.

And if you’re not satisfied with any other Dash parts, try “myunity“ and it may help you adjust Dash, such as add “Display Desktop” button in Dash laucher, resize Dash launcher, show system icons on desktop and etc.