The basics of setting intonation are here in this thread. Compare the open string or its 12th fret harmonic, either one is equally valid* if your strings are in good shape (and if the strings aren't in good shape, none of this will really matter anyway) to the fretted note at the 12th fret. The open string/harmonic is your standard, and you need to adjust the fretted note to match that. If the fretted note is too sharp, that means the string is too short; if the fretted note is flat of the standard, then the string is too long.
If the fretted note is sharp, move the saddle away from the nut, retune and check again. Always retune and check again after every saddle move. If the fretted note is flat compared to the standard, move the saddle towards the nut. Some trial and error as you dial it in but after a while you get the hang of it and can do this pretty quickly. No good reason to pay someone to set intonation when you can get a good tuner for so cheap.
John
*The 12th fret and 5th/17th fret harmonics ARE exact octaves of the open string so there's absolutely no reason to avoid using them in favor of the open string. And, given that they vibrate at a higher frequency, your tuner has a better chance of counting the vibrations accurately (a higher sampling rate as it were) than with the open string.