Having sidebar issue after customize theme.

I tried some customization in theme after this On my secondary pages I have used the “right sidebar” template but the sidebar are not showing. I would like to have different sidebar “sections/boxes” for different items (I have already customized the sidebar in a child theme to have a border and shading so it is an actual box).

This is what I am looking to do – Example:
“Join mailing list” in top sidebar box
Some other info in second box
Contact me info in third box
etc.

How can I make additional sidebar sections?
https://myboxingheadgear.com/
Thank you in advance!