I am looking for a map on the web may be an ArcGIS online map that will allow an user to enter an address and return lat,long coordinates for this address.
By default ArcGIS Online Web Maps contain a geocode search feature that takes an address as input and returns the XY location on the map:
My guess is that you are looking to display the XY coordinates in the result's pop-up after searching for an address?
Hope this helps,
Retrieving data ...