Adding my navigation bar component to an existing project

I am working on a project to create a college website. My friend made a react-app for each of the respective pages and pushed it to our repo on github. When I pulled the code those codes did not work. Also I am unable to figure out how to insert my own react-app for navigation bar to those existing projects.

https://github.com/CSAIDept/react-homePage This is the homepage he created. https://github.com/CSAIDept/dept-website/tree/master/Reusable%20Components/navbar I need to add this to the page.