* install Gmaps module
* Enable GMap and Gmap Macro Builder
* Go to Site Configuration -> Input Formats -> Configure
* Tick GMAP macro expander
* Save
* Go back in and go makesure GMAP is at the bottom
* Click on 'Build a Gmap Macro' on the menu
* Create a map and copy the code into your node
I also recommend moving the 'Build a Gmap Macro' down to the create content menu so it's not so in your face

