Question: how to customize/remaster FreeBSD become DragonflyBSD

[Stefan N]

Dear Sir/Madam,My name is Stefan and I am interes
ted to learn more about FreeBSD. I found the email address from the DragonflyBSD webpage. Anyway,
 I have found some derivative version of freebsd like DragonflyBSD which is based on FreeBSD.How is the method for customizing/remastering freebsd to be "our own flavour BSD with its uname"? The most interesting part is that when I type 
uname -ar, it was shown their own 'BSD version'. Thank you in advance.Regards,Stefan