Connecting to webservice

Question

Hi

I developed an app that will require its users to use 16 digit PIN to log in before accessing the app. my questions are

1. when the user input the 16 digit pin and they click activate button the app will send request to the webservice

to confirm if the pin is genuine or not If the pin is genuine it will navigate the user to home page of the 

app i.e access granted, but if the pin is not genuine it will show error how can this be achieved 

2. what are the differeces between SOAP, httprequest and webservice (if there is a beginner tutorials for this please share)


I wait your reply