Sticky sidebar for my site

Hello everyone,

I am new here and relatively new to the CSS scene as well. I am still in school for it so definitely not an expert. Anyway, my church has asked me to help redesign their website. It has not had anything done for years and is in rough shape, so there is a lot to do.

One of the first things I'm working on is adjusting this page (Ways to Connect) to work with anchor links. I have the anchor links working, but what I'd like is for the sidebar to be centered on the page (ignoring the logo and nav at the top and footer at the bottom, so at the top of the page you won't see much but once you scroll past that it will be sticky and stay centered on the page) so that when you click one of its links and it jumps down the page, the sidebar will come with it so you don't have to scroll back up to click a different link. Any ideas on how to do this?

Hopefully that all made sense. Thank you all for your help in advance, it is much appreciated!

FYI: It is hosted by Squarespace. So I haven't done any coding yet, just looking to add some custom CSS.

-Jacob