Getting my create-react-app running

Hello all! So I followed a tutorial to get my create-react-app application to display on github pages. It is displaying on github pages fine, but my problem is that I can’t push the actual code up to github? It continues to throw this error:

error: failed to push some refs to ‘git@github.com:JustinWarren/my-jamz-app.git’ hint: Updates were rejected because the tip of your current branch is behind hint: its remote counterpart. Integrate the remote changes (e.g. hint: ‘git pull …’) before pushing again. hint: See the ‘Note about fast-forwards’ in ‘git push --help’ for details.

I’ve used Github a bunch but haven’t ever tried to use github pages to deploy a create-react-app. Any help would be greatly appreciated!