Open the song you'd like to print.
Tap the Share button in the top right corner (square with an arrow).
Tap Chord Chart and then PDF.
Now you can:
• Print it directly from your iPhone/iPad if you have an AirPrint enabled printer
• Email it to yourself and print it from a computer.

If you want the chord diagrams in the chart, turn on the Chord font you want, here is how.

In case you have a chart that has only 4-5 systems, the printer might default to landscape.
Open the Editor and add an extra character 2-3 lines under the last bar to make sure the chart will be printed in portrait.