'heroku' does not appear to be a git repository

You could try the following in your root directory:

// initialize git for your project, add the changes and perform a commit

git init
git add .
git commit -m "first commit"

// create heroku app and push to heroku

heroku create
git push heroku master

Not sure where you are in the process. You also don't need github to deploy on heroku, just git. Hope this helps!

To add a Heroku app as a Git remote, you need to execute heroku git:remote -a yourapp.

Source: Deploying with Git

First, make sure you're logged into heroku:

heroku login 

Enter your credentials.

It's common to get this error when using a cloned git repo onto a new machine. Even if your heroku credentials are already on the machine, there is no link between the cloned repo and heroku locally yet. To do this, cd into the root dir of the cloned repo and run

heroku git:remote -a yourapp