The cushion indicator is on the front of the cushion next to the arrow that points to the arrow on the frame for connection. The frame size indicator is on the top of the frame behind the elbow connection.
You can see which size is right for you using the fitting guide provided with your mask.
You can find more fitting guide instructions and videos at https://www.sleepapnea.com/products/masks/dreamwear/pillows-right-fit/.
If you are still having trouble when fitting your mask, consult your user guide for complete fitting instructions.