Teresa is growing a herb garden this year, it's kinda fun, she's got oregeno and rosemary. She just sicked me on figuring out when and how to harvest them.
Information on growing and drying herbs in general:
Oregano
Strip the leaves off the stems. To use fresh oregano, hold the rinsed and dried stems in one hand and strip off the leaves by running your fingers of the other hand down the stems. Use whole leaves or chop them with a sharp, dry knife. The Italians traditionally also use the buds just before they flower.
Dry your own fresh oregano. If you have an excess of fresh oregano, you can dry it by tying the stems together and hanging it in a warm, dry, well-ventilated place. Oregano dried at its peak will likely have more flavour than supermarket varieties, which can vary in age. I store my homemade dry oregano en branche, as the French say, in a paper bag in a dark place, and crumble the leaves off the branches as I need them. Storing the whole branches helps keep the volatile oils intact.
Rosemary
Harvest before the plant begins to flower, never cutting off more than one third of the plant at one time. Rosemary is one herb that can be used either fresh or dried, although it's pungent, bitter flavor should be used sparingly. Store fresh rosemary in the refrigerator, by wrapping in damp paper towels and then placing it in a plastic bag poked with a number of holes first. You can also keep it as you would cut flowers, in a vase with fresh water. To dry, simply hang the rosemary sprigs in a dry room with good air circulation, or lay the sprigs spaced out on a screen Once dry, store in jars with tightly closed lids in a dark place.
Source: http://www.italianfoodforever.com/articles/article55.php