The important part is here:
gprsSerial.println("AT+HTTPPARA=\"URL\",\"http://foro.battlepvpmine.es/get_buzzing.php?key=8A621E21A96A6E36\"");// setting the httppara,
//the second parameter is the website from where you want to access data
delay(3000);
toSerial();
gprsSerial.println();
gprsSerial.println("AT+HTTPACTION=0");//submit the GET request
gprsSerial.println("AT+HTTPREAD");
delay(3000);