F2C KML Feed is just that, a XML data type tool, you need to install 3rd party software to visualise it. I use mike ruemers google maps plugin which can load KML Feeds. Please note, it is VERY sensitive to spaces in code so get it to work with his demo code first before starting with F2C KML feeds!!
F2C 'only' generates the feed and the data in it. But, since it's a CCK you get to decide (through templating) what you want to show within the marker's or even within the feed.
You will need F2C Pro with a geocoder field in your form
You will need at least ONE GeoCoder filed in your form for the location. Converting addresses (as placemarker) to geo location by Google Maps is no longer supported by Google:
F2C KML & F2C Search
F2C Search and KML Feeds are two different extensions which do not interact. In other words, you cannot use F2C Search to dynamically change or generate a KML Feed.
Google Maps is not Google Earth
PLEASE NOTE, google maps has many limitations compared to google Earth so you can't just use any elements in the KML markup (once you get this far).
Learn about KML feeds!!
Please learn about what KML Feeds are and how they work with Google Maps. Don't just look at our demo and think it comes out of the box. Form2Content is a CCK, a tool, you need to use it properly ;)
Test your KML Feed!
You can try the feedvalidator to check/test the KML link in the F2C back-end: