The first thing to do is configuring your app. Here are the steps for getting Client ID and Client Secret:
1. Go to the Google Developer console.
2. Create a new project if you don’t have any project or you can select an already existing project.
3. In the left sidebar, expand APIs & auth section.
4. From the left sidebar, select Credentials
5. This will show Client ID & Client Secret of an already existing project or you can create a new Client ID by clicking on the button “Create a new Client ID”.
6. Now you can find Client ID & Client Secret for the project.
Feel free to drop any comment or you can also reach me by dropping an email at firstname.lastname@example.org.