When you go this Google Console Link
Now check I agree (please dont ask me why.If you are patient read entired terms of service) and click on Agree and continue.That will open a page like below
Click on create Project. That will open a dialouge like this. click on create and change name if you want
Creating project will take you to dashboad which contains beolw. Now click on API & Services and select Credentials
Tha will take you to following.
Select OAuth client ID which will take you to following
Select create and Fill the required information of below
At the bottom you will have Save and continue that will take you to scopes page and there also click save and continue until you go to summary there you click on go to dashboard
Then in dashboard click on OAuth client ID which will ask you to select Appication type according to your need
That will pop open a board
You can click Download json and it will download the file
You can also create an API from create credentials and clicking on API key but you inorder to use specific API's you have to enable them from Library on side bar which will open
and search for for example "Google Sheets API" which will get
click on API and click Enable which will enable that particular API
