Linux/Mac OS X
==============
To install doxygen: 
$sudo apt-get install doxygen

If the above does not work go to:
http://www.stack.nl/~dimitri/doxygen/download.html for the correct download.

Then go to the following website for inforamtion on the install:
http://www.stack.nl/~dimitri/doxygen/install.html

Then to generate the html, run the following code while you are in the qgroundcontrol/doc directory:
$doxygen Doxyfile

The html file index.html should be in doc/html unless you changed the output directory. 

The other option for generating the documentation is to use the wizard:
$doxywizard &

doxywizard information:
http://www.stack.nl/~dimitri/doxygen/doxywizard_usage.html

Or go to the Doxygen Manual for information at the website noted below.

Windows
=======
Go to the following website for the correct download and follow the wizard to install:
http://www.stack.nl/~dimitri/doxygen/download.html

Run the wizard to generate the documentation. 
Go to the website below or the Doxygen Manual for information on running doxywizard.
http://www.stack.nl/~dimitri/doxygen/doxywizard_usage.html

Doxygen Manual
==============
http://www.stack.nl/~dimitri/doxygen/