There are a few essential things you need to know before you start using ProChords.
So let me introduce the basic elements of ProChords User interface

The Arrow Pointer:
The arrow in top of the screen indicates which of the chords above will be affected by your action.

The Progression Band:
When you open the interface, you will find that there is a single chord pre chosen. This chord constitutes the first chord in the song you are about to write. And the first of any number of chords you can add from here on. The sequence of chords you choose is referred to as your Progression Band. The chosen chords can be dragged back and forwards by using your finger on the screen.

Read How to add a chord or Download ProChords for your iPhone