Crop oval and remove white background

I am trying to crop an oval section of a photo and remove the background (making it transparent) using PSE 13. The step-by-step instructions indicate the use of a "trim" tool. I see no such tool in my PSE editor. When I try to proceed without the steps that refer to the trim tool my image shows a checkerboard pattern on the part of the image that I want removed but the resultant saved PNG image shows the checkerboard part as white instead of transparent. Thanks in advance for the help.