For an overview of Delta Client go to the Delta Client repository. This is just the website for that project.
The Delta Client contributing guidelines should have all the information you need to get started contributing for this website.
Here's the simplest way to setup the development environment;
# setup
git clone https://github.com/stackotter/delta-website # or your fork
cd delta-website
npm install
# start the development server and open it in the browser automatically
npm run dev -- --open