Mutt has a global configuration file in either /etc/Muttrc or /usr/local/share/mutt/Muttrc. This is useful for configuring system wide settings. But to configure your own account you have to configure your personalized muttrc file in your home directory at ~/.muttrc.
Here is a sample muttrc file that can get yo start off with mutt. Explanations are given as comments.
## Set your imap server name and port here.
set folder=imaps://my.imap.server.name:imapPort/
## Where to look for the mails
## the "+" simbol means, append this to the value of "folder" setting
set spoolfile=+Inbox
## Your imap username
set imap_user=my_imap_user
## Set your imap password - Not preferred for security reasons
## If not provided mutt will prompt you for a password
set imap_pass=my_imap_pass
## Setting sent folder ( note the "+" sign )
set record=+Sent
## Setting draft folder ( note the "+" sign )
set postponed=+Drafts
## To cache downloaded header
## Good for performance
## directory should be manually created
set header_cache=~/.mutt/cache/headers
set message_cachedir=~/.mutt/cache/bodies
## Your preferred editor for composing
set editor=vim
## How to sort your mail
set sort='last-date-received'
