detect me and others a map using GPS

I need a programmer who can create an app that can be the following: # it must be able to detect where you are - using GPS # it must be able to put a marker - the location 'here I am' - and write what time you put the marker # users can remove marker again – when its no longer useful # markers must be reported to a server - so that others can see the marker # it must record and play a sound - when you visit other members 'markers' - within different radii (10 km, 25 km, 50 km.) # you should be able to enter the 'markers' manually - by entering an address # it must be able to display all detected markers - on the whole map. Additionally, I need a programmer who can create software for the server - and help to set up server.