Getting going with JSparks is as easy as 1-2-3
The Arduino sketch has been built with all of the logic needed to run JSparks. Simply download it here and then follow the usual procedure to upload a sketch to Sparki. If you aren't familiar with those steps, ArcBotics has an excellent tutorial. Simply swap out the "example" code they have in the instructions with File -> Open and then selecting the serial_controller.ino file you just downloaded
Go to the JSparks IDE at https://sparki.eskibars.com/ide/ and register an account. Create code by dragging and dropping blocks around and then click the button to view the resulting JavaScript code and the button to push it over to your Android device. You should get a push notification on your device, which will download the code which you will be able to run from the "Programs" feature.