Head over to your Google API Console from here Create a Project and switch to the project and head over to the Google APIs library and enable Google Drive API.
You should have something like this :
Click on create Credentials and select Web Server and check on Application Data and create a service account name and click on continue to select role , which would be as an editor and then you will get a generated JSON, which is your secret file , place it in your app directory.
Now , go to your google sheet click on share and go back to your client secret , and copy the client email and give edit permissions to this email address only !
You are good to go !