To play the text shown on the page, click and select the part you want to be read out to you then press the play button.
To pause it click on the red pause icon. To stop it click on the black stop button. To increase the volume click on the volume icon.
To change the text size, click on one of the 4 circle icons with the letter A in it.
To change the contrast click on one of the circle icons that are half filled.