adding canvas using Photo Elements 2021

@Fellflobber, thanks for letting us know what the problem was.  I almost never use Quick Mode, so I easily forget that only a limited set of commands are available there.  Great photo, by the way.

The Content Aware fill does a great job with your photo:

When you say that the Edit>Fill option is not active, did you actually try to click on it?  (I agree that the menu choice appears to be a lighter grey than other active options in the menu, but no matter what I have tried the option is always available.)

If that is not the problem, then have you actually selected the blank canvas e.g. with the Rectangular Marquee tool? 

Alternatively, does your edit have multiple layers?  And if so, which layer are you selecting?

If the tool is still not working for you, try resetting the preferences file. Go to Edit>Preferences>General tab and click the Reset Preferences on next launch button.

When you resize your canvas using the cropping tool it fills i nthe new canvas with your background color. 

I just select the cropping tool, and drag it around the entire image- then adust the canvas size. 

I'm not sure I understand what you are trying to do or what you are have done.

Are you trying to increase the size of an image by adding to the canvas/border area and then filling that empty canvas with Content Aware pixels?  If so, you need to first add to the size of the canvas so that your current image is bound by a new (background color) border.  Then you need to select the border pixels (by using the Magic Wand).  Finally, in the Edit>Fill Selection dialog, use the Content Aware option from the drop down menu.  The selected border will then be filled with an extension of the image.

If this is not what you mean, please gives us more details of your issue.

I've moved this from the Using the Community forum (which is the forum for issues using the forums) to the Photoshop Elements forum so that proper help can be offered.