Any application that uses OAuth 2.0 to access Google APIs must have authorization credentials that identify the application to Google's OAuth 2.0 server.
Assuming that you have enabled the needed API
how do you create credentials for your application
how your application will use the credentials to access APIs that you have enabled for your project
Can anyone explain it to me?
Go to Google developer console and create your project there, it will depend upon which type of application you are building which type of client credentials you create.
Web, Native, mobile
Your application will need to request consent of the user once that consent is granted you will be given an authorization code, then your application must exchange the authorization code along with your client credentials in order to create an access token which will grant you access to the users data.
Depending upon which language you are using i recommend looking for a client library to help you with the authorization steps.
This might help as well Google development for beginners.
