Your first question, when is it "ripe", actually is better to know. You need to look at the trichs, the tiny glandular bubbles on the outside of the pistils. To look you need a microscope or loupe or some other way to magnify somewhere in the range of 15-75x. Trichs will be clear during flower and start to turn cloudy and then amber as they finish off. Peak time is between mostly cloudy and mostly amber -- if you harvest before amber shows you will get more of a trippy head high and harvest when leaning amber you will get more of a body couchlock high. Check the pictures here, look at the fourth graphic. Radio Shack has a pocket microscope for about $10. Buds often are ready around 8 weeks of flowering but varies by strain and conditions, could be a little quicker or could be up to several weeks longer.
ok, as you know im a beginner. so your going to have to specify what your talking about. what do i magnify?
Snip off one pistil (hair) from a bud. Put it on a slide or white piece of paper. Under magnification you will see that it is covered in globular-looking sacs as seen in the chart I referenced. Check the coloration against the chart to know when it's harvest time.