Second, you should update icon links in _includes/particles-home.html and add/remove icons as needed. You might want to add icons that are not included in the theme by default. For more information on how to do this, see this post.
Third, you should customize the file _includes/contact.html by inputting your contact details and adding/removing lines as needed. This information is prepended to your CV.
Fourth, you might want to edit the style variables specified in _sass/_variables.scss. These allow you to customize the theme's color scheme and typefaces. There are many resources on the web to learn the principles of good web design. I personally recommend Matthew Butterick's Practical Typography.
In addition to these files, you can customize favicons in the assets folder. For that, favicon.io is an excellent tool. You can also change the particles.js configurations in assets/json. The library homepage features an interactive tool from which you can export a new configuration.
This repo includes a docker-compose file that allows you to quickly setup a container running Jekyll. If you don't already have Docker and docker-compose installed, you can install them using the following guides from Docker:
Install Guides
To start the container simply run:
docker-compose up
Alternatively you can run the container without docker-compose using the following command on Mac/Linux:
docker run -p 4000:4000 -v $(pwd):/site bretfisher/jekyll-serve