Here is the solution.
Step 1: Install Locations Module
Step 2: Install Gmap Module
Step 3: Enable Gmap Location Module Which is part of Gmap Module.
Step 4: Set the Google Map Key Here admin/settings/gmap
Step 5: Go here admin/settings/location/main and select default country and check Use a Google Map to set latitude and longitude
Step 6: Go to content type edit tab and select Locations Collapsible tab, under that go to Number Of Locations and set min, max, Number of locations that can be added at once as 1,1,1 respectively
Step 7: Go to your nodes click on edit and you can see location settings, there give the address and longitude and latitude which you can pick from map or you can set. Longitude and Latitude are very important to locate a node in map
Step 8: Save the node.
Step 9: admin/settings/gmap_location go here, under node map select marker action as open link.
Step 10: Now go to map/node you can see all your nodes here.
Step 11: If you want to enable map for nodes go to blocks, enable the block called Location Map
That's it you are done.