I have two apple trees. I have lived here for three years and I am sure they are a couple of years older than that. They are both producing fruit but I do not know how to water them. Do I put a ring in the dirt around them about ten inches from the base and soak them once in a while, or do I just water the ground. How often do I water them. And how do I prevent the little pin hole size bad spots on the fruit? I live in northern California just above Sonora at about 3000 feet.
I didn't need to water any of my fruit trees regularly in Ontario, but when they were new the advice I was given was to get a large bucket and put a small hole in the bottom, then put the bucket near the base of the tree and fill it with water. This would release water into the ground slowly enough that it could soak in rather than running off.
If your trees are looking healthy and the leaves are not wilting, they are unlikely to need watering. If you are having a drought, this technique will probably work. You could also put on a sprinkler near them so their root area (which typically mirrors their branch area) is getting water.
I'm in zone 7A and get around 43 inches of rainfall a year. Not all that different from where you are. Other than when my trees were young - first year or so - I've only given them water when we hadn't had rain for more than 10 days or so. The roots tend to grow pretty far down (ask me how I know!) and are able to extract water from the soil quite well. I honestly don't think you need to generally do supplemental watering unless you're in drought conditions.
You might find some useful info here on spots on apples. I'd bookmarked it a few years ago when I was trying to diagnose a problem I was having.
Five (or more) year old fruit trees shouldn't need supplemental water if you get enough rain. If you are experiencing a drought, you should water deeply and infrequently. E.g. the bucket-drip method that Kate Gregory mentions, every other week, making sure that you use plenty of water so that it gets deep to the roots.
Frequent watering with small amounts will encourage the tree to form shallow roots, and without deep roots it will be unable to secure its own water from deep in the soil.
I get about 40-45" of rainfall annually, and except for the first year I don't irrigate on a regular basis. Last year during the drought I gave each tree 2 x 5g pails of water every other week. (Bathtub water works well for this.)