How do i give inputs and grab output into an Android application from a website?

I have a Wifi Router,I have been given an Ip address to visit where I can configure all the Settings for the router like username ,password,SSID,mac filtering etc.I want to develop an Android application where I like to get the notification when someone who already connected to my wifi ..enters my wifi zone,to easily add/remove mac addresses to Mac Filtering etc. How can I develop such an Android Application? I know Core Java and a little bit of Android Programming. What else I need to learn to achieve this?