Watercolor paint generally dries quickly, unless you are working really wet. There are a variety of techniques that can be used to create watercolor paintings, such as painting wet-on-wet (very wet brush and wet paper), or wet-on-dry (wet brush on dry paper). You can also create different effects by splattering, using salt, or wax resists. These are just a few of the many watercolor painting techniques.
Although the paint dries quickly on the paper, dried watercolor paint rewets easily. Dried watercolor paint is always susceptible to being "reactivated" as soon as it comes into contact with water. This can be used to great effect, such as laying over another layer of color or details, but it is also something to be careful about. On the other hand, it's okay if the paint dries out on the palette, as it will rewet once you add water. This means that it's very hard to "waste" watercolor paint, because all you need to do is cover the palette and save it for later.
Once finished, watercolor paintings will need to be sealed with a protective spray. An archival spray will seal the colors and protect the surface of the painting. There are innovative, multi-step techniques for displaying watercolors without a frame, but traditionally watercolor paintings will need to be framed for display.
This is basic information you'll need if you want to learn how to watercolor. The next step is to buy yourself a set of watercolors and go for it!