error: src refspec master does not match any solution

Solved! Here is how I solved this issue:

1. Made an app on Heroku first and prepared all the codes in local_folder to push into it.
2. Cloned the remote app using heroku git:clone -a app_name
3. then cd app_name
4. then copied all the codes into this folder from local_folder
5. then git add .
6. then git commit -am "initial commit"
7. then git push heroku master
8. Viola!