For the most part you can just edit the files via the github repo (asking for writing permission or at least pull request permission may be necessary. Ask a competent lifeguard on the matter or Danny). All of the base documents follow the markdown file format (simpler html effectively). See the following guides if some more detailed descriptions on markdown is desired.
The current theme as 12-20-21 is Hydeout. Do note the remote theme option in jekyll is being used here which could cause problems in the future. So potentially update with a local version of this theme (a somewhat annoying process so has been pushed back to a different date). Checkout that Repo for information on theme modification for the most part but simple notes.
To add a page to the sidebar just include
sidebar_link: true
in the top page definition section (probably fair to just copy existing pages to resolve this issue).
This is somewhat a pain to do but I will cover the very basics (probably will have a VM dedicated somewhere for local website testing).
domain: interplanetarylab.github.io
url: https://interplanetarylab.github.io
baseurl: / # change to /testing-website/ for git pages
bundle update
bundle exec jekyll build
bundle exec jekyll serve --host=0.0.0.0
Now a local copy should be accessible from your local machine (plus other machines on the network. Do Note This).
Currently the publications page gets auto update with a github actions bash script. Probably could be done more efficiently but for now it works. However, the trigger is set to pushes to the Website repo not the publication repo. So that should be changed at somepoint.