[Exim] Exim Installation. - Please help

Hi,

I have just installed exim on a linux box as an alternative to sendmail. To
test the installation I use exim -bV command and I don't get errors. I
then try some simple routing tests:

exim -v -bt fred

I get the error: unknown local part "fred" in domain "my.domain"

I know this is probably a basic question of setting up a mail server but
where do I specify "fred" as a local username ? I am looking in the
configure.default file but I am really unsure of what I need to set as all I
want is a basic configuration initially. The documentation is really
ambiguous.

When it comes to switching exim on again the documentation only hints about
how this is to be done. I know how to stop sendmail but I don't know how to
get exim to start in its place.

Please help.

Dan