When cooking with fresh and dry herbs, there is a general rule when it comes to the ratio of fresh to dry. Because dried herbs are generally more potent and concentrated than fresh herbs, you'll need less -- typically three times the amount of fresh herbs as dry. For example, if a recipe calls for 1 tablespoon of fresh oregano, you need only 1 teaspoon of dried, since 3 teaspoons equal 1 tablespoon.
Fresh-cut herbs can be wrapped in a paper towel, stored in resealable plastic bags, and then put into the refrigerator. Dried herbs should be stored out of the light and in a cool, dry place. Keep an eye on how long your herbs have been open -- if they've been open for too long, they'll smell and taste less potent.