如何使用php api连接windows8 app c＃

I have this code in which i am trying to connect to a php base api server for a windows8 application.however I am not getting any result knowing that if i try to debug it the url is correct and the variables are set. i am new in windows8 app and c#, and after several researches this is what connecting to an api server looked like Any help pleaseI have this code in which i am trying to connec