Mirror a chunk on every page

The easiest way is to add it to the home page and inherit it on all pages of the site. If you only need it on one section, then you could put it on the top-level parent page and inherit it. If you need it on multiple sections, you'd make a copy of it to each parent page for each section, then inherit it down. Technically it will let you mirror to all the parent pages then inherit, but it may cause issues if you mix those two. It's best to make a copied chunk on each parent page then inherit to the pages of that section.

To inherit a chunk, right click on it and click Cascade: On.