mutt maildir and enviroment variables

[RYAN vAN GINNEKEN]

Ok i need some help with Mutt but not really mutt more just Freebsd in 
general

I run freebsd 4.8 something
mutt version 1.4 something
postfix 2.0.0.16
bincimap version 1.2.3

when i execute the command
#mutt
 i get an empty /var/mail/user mailbox
i use Maildir and my mail box is /usr/home/user/Maildir
so if i execute this command
#mutt -f /usr/home/user/Maildir
everything works fine and i can read my mail
so how do i set mutt to read this mailbox instead of  /var/mail/user
i tried the .muttrc .mailrc .bashrc .chsrfile in my users home directory
i tried the .cshrc .profile file in the / directory
please can someone tell me where to set this variable so that i only 
have to do it once and it will work for all the new users i create as 
well  please

p.s.  a general overview on making these type of setting and which files 
to make them in would be much appreciated as my system is getting messy 
and i cant remember all the changes i have made or to what files i have 
made them.