How do i finalise an Auto Selection in PS Elements 2018

Hi,   i have gone through successfully doing an Auto Selection on one of my photographs.  After getting the "marching Ants" around my selection, and being happy with the result.  I cannot complete the process!!  I have pressed the normal select/ok Key (return), and this with loads of other keys, but this has not completed the task.  I even thought that perhaps the "return key" was at fault, but this is not the case as in everything else it works fine.  I am using a 2017 MacBook Pro OS 10.12.6  Sierra.  Can anybody advise?

Photoshop Elements​