LIQUIFY Not Working

I am a newbie to Photoshop but, thanks to Google and Youtube, I'm finding my way.  However...I have had consistent problems with Liquify not working.  I'm not a super savvy tech person, and I'm just not finding a solution.  I've gotten an error pop-upto say that said something about the background setting not allowing me to see changes (I DID click "don't show me again" as some suggested with no luck.)

I know this may be basic, but might anyone share the very basic step-by-step?  I duplicated the background, converted to smart object, then went into LIQUIFY.  Zero movement, even now that I don't see the pop-up.

I'm not seeing anything at all, as in zero changes.  So it isn't a sheer movement and opacity thing.

Thank you for any help, guidance, or suggestions.  I have Googled the heck out of this and nothing is working.