There are a few different techniques for giving text and shapes a shadow. The shapes shadow option in the inspector palette and drop shadow filter methods are described below. Since text and shapes are essentially treated the same (they are both vector based), text will be used as the example.
Shapes Shadow Option
Click on the bottommost option in the inspector palette which is the Shape Shadow:
Check the shadow box, then adjust the blur and shadow position. To adjust the color, click on the color well to bring up the colors palette.
Drop Shadow Filter
Go to Filter ▸ Stylize ▸ Drop Shadow. You can adjust the way your drop shadow looks by using the Y Offset, X Offset, and the Blur Radius sliders. You can also change the color of your shadow by clicking on the shadow color well to bring up the colors palette. You can see the changes you make in real time on your text.