How to support multiple Environments on Heroku?

Question

git

There is a working project on heroku.
There is a staging version, there is a production version. They are implemented as separate applications. There may have been a shared repository with code once, but it doesn't exist now.
The project needs to be finalized, I merged the sources from both versions separately.
Now the question is how to combine this business into one repository so that you can commit (i.e. deploy) from it to both staging and production in heroku?
I tried to do it according to the heroku manual, but for some reason commits to staging do not lead to deployment, just a regular push happens.

Answer 1

Was that the order?

$ git add .
$ git commit -am "make it better"
$ git push heroku master