The sample at the left is constructed of three layers. To adjust the angle, simply click on the angle flyout and click where you would like the new light source to be, or click and drag to your desired setting. If you know the angle you wish to use, you can also type the value. With the Use Global Angle option checked, this adjustment will change the angle across the entire image. Uncheck the Use Global Angle option, and you can change the setting for the active layer without affecting other layers.
Intensity is increased in the lower sample, with all other values remaining the same.
The distance, blur and intensity settings create the effect that the object is rising above the page. A low distance value will make the object appear to be quite close to the page, while a high setting provides the illusion that the object is floating well above the page. A closer setting is often better for text. The blur setting provides control over the amount of feathering in the shadow edges. I often find that I reduce the distance and increase the feathering in drop shadows.