How do I add a location to my path in Unix?

Aha, FreeBSD. That's tcsh, I believe.

So:

set path=(/sbin $path)

bash & zsh syntax:

export PATH=${PATH}:/sbin

sh syntax (two separate commands):

PATH=${PATH}:/sbin
export PATH

csh and tcsh:

setenv PATH "${PATH}:/sbin"
set path=($path /sbin)

This will append /sbin to your path, so when you type abc, the shell will also look in /sbin for it. You can also add the command to your ~/.bashrc file (or ~/.cshrc, ~/.tcshrc, ~/.profile, ~/.login—depending on which shell you use).