how to store 'client_secret' and 'client_id' on Android app when using OAuth?

I am developing an android app for the existing website, so i developing login part to the an android app and i use oAuth protocol.i have API for the users data and generate the client_id and the client_secret_key from the web site.so my question is.

• How to store this client_id and client_secret (in mobile app or any backed client web service)
• When i use backed client web app to store client id and secret how i authenticate users.

The web site built on the larevel php framework.

via Chmath Kalubovila