Connect android app to webservice

Question

Hi everyone

I need a tutorial on how to connect my android app to the webservice
In order for users to login into the app before usage
If the login details matches the parameters or details given it will take the user to the home page
but if not it will prompt the user to register or sign up before usage

I will like the tutorials to be either using asp.net with android or php, mysql with android

Thank you in advance i await your response