Vehicle tracking system GPS GSM

how do I trigger Arduino mega to send me location on an android app that I created for the vehicle tracking system? I only found articles on vehicle tracking system when a user either calls the sim used in Arduino or sends SMS to the sim used in Arduino. I am new to this and doing a project for which I have created an android mobile application. It would be a great help if somebody could answer my query

Presumably you don't want to use a GSM based system because of the costs of using the mobile phone system. This leaves the GPS system, which communicates directly with several satellites, and has accurate timing systems built-in.

You will need to interface the GPS receiver you have with the Arduino, then process the signals you receive - there are already many cheap devices for doing this, not least the car Sat-nag, however if you want that, or your system using position data, to SEND that to the t'interWeb then you're going to have to pay some organisation to transfer your data to whichever mobile phone or device you choose. These are the poeple who spend large amounts of money building mobile phone antennae, and buying Govt. licences, and they're not giving away bandwidth for free.

I hope this is helpful.

This is not a project for an advanced user This is for a well trained expert.