Newbie basic layour query

I am really struggling to understand which guidelines I need to use so my site can be viewed on both a PC and a mobile. Sadly after reading lots of guides I am only more confused.
I have roughly laid out three pages and added a menu to the left. But on a mobile the menu does not show. If i keep the the unshaded area in the middle, I am wasting so much space when viewed on a PC. It’s only simple if you know the answer!
Any help appreciated. My site is…
https://ebbs101.wixsite.com/cavesofnorthwales

This forum is for all code related issues, you would be much better suited going through Wix Support for more help and info about your question.
https://support.wix.com/en/about-wix/contacting-wix-support

https://support.wix.com/en/article/finding-your-mobile-menu-in-the-mobile-editor

Your website will always be able to be viewed through desktop, mobile or tablet, you have access to the desktop editor for desktop versions and the mobile editor for the mobile versions.
https://support.wix.com/en/the-wix-editor/editor-basics
https://support.wix.com/en/article/about-the-mobile-editor

You can read all the Wix Support pages about using Wix too.
https://support.wix.com/en/

OK thank you for the support link

May I just add that this forum’s name is: Community discussion (not coding issues), so how have I made a mistake?

Thanks for the reply. Being a newbie I searched for “wix forum” and this one came up. Please excuse me for not knowing that Corvid is understood by others as a coding forum. I simply assumed ‘Corvid’ was a company hosting Wix’s forum. How can you forgive me?