Programming the FCB1010 - UnO is not easy (look at Howto).
Fortunaly there are several very good free editors on the web.

I use the Ripwerx FCB1010 Editor v2.0 created by Mike Riley.
It's written in java which makes it platform independent (it runs on windows, apple and linux).

The latest java software can be found here.

Another good fcb1010 editor is Ed Dixon's graphical FCB interface.
(windows only)

Ossandust, the maker of the UnO chip, has released a wonderfull editor recently: The FCB/UnO ControlCenter (for Windows and Mac)