[luau] Running a script

[Miguel]

I downloaded an "E-mail Server" software for linux called eXtremail, i've 
installed it but i cant get it to start (the daemon) the instructions say to 
type "smtpd start" in the command prompt but it gives me this error 
"bash: smtpd: command not found" ive tried going in to the directory in wich 
the file is located but its not helping much....it still give me the same 
error.

am i missing something?

the instructions say that the executable follows the same rules as any other 
executable, which means, that if not on tha path enviroment variable, i need 
to tell the shell where to find it.

who do i do that?