I read around the net that 1 is low and 3 is high, but it's opposite on my bike. Is this correct? I have a Sturmy-Archer src3 ll.
On a derailleur bike, its easier to see this. Let the gear ratio be the # of teeth in the front chainring divided by the # of teeth on the rear cassette. Higher gears have higher gear ratio, lower gears have lower gear ratio (so if you keep whats in the front fixed, smaller cogs in the back correspond to higher gearing).
Lower gears will be easier to pedal than higher ones. Usually, these are numbered on the shifter the same way you would have on a car/motorcycle (1 is low gear, the big cog in the back, 2 is the second biggest, etc.). But nobody's really stopping you from numbering them in the opposite way.
You have an internal gear hub, so you can't see it, but the lower gears will be the easiest ones to start from.