Consuming a WebService in PHP

I set up a WebService in PHP and need to know how to consume it, whenever I do a search on it it returns me like this:

All Alerts:

get_all_alerts.php

{"table_alerts":[{"id":"1",
                      "category":"Visitante",
                      "name":"Rosana",
                      "city":"Sao Paulo",
                      "description":
                      "Veio tirar ferias...",
                      "created_at":"2015-02-25 16:53:23"},
                  {"id":"2",
                      "category":"Visitante",
                      "name":"Sergio",
                      "city":"Santa Cruz",
                      "description":"Mudou de Cidade",
                      "created_at":"2015-02-25 16:54:51"}],"success":1}

How do I get this data and display it in a ListView on Android? I've already tried using this tutorial but I could not , it could not convert the value. Could anyone provide a simple tutorial on how to do this?