I obtained this board some years ago. The Arduino development environment is offered to edit, compile, download and run your programs.
http://arduino.cc/en/Guide/Windows#.UxcpBD9_vec
If you prefer, you can also write your programs in more popular languages such as C.
There are many CW Keyer programs for Arduino. One example is:
http://blog.radioartisan.com/arduino-cw-keyer/
Or you can write your own program best suited for your purposes.