Patti,
The field description is displayed in a tooltip when you hover over the field's control or caption. While this isn't a Kentico-specific question, it should be possible using CSS according to these stackoverflow solutions: https://stackoverflow.com/questions/9927640/styling-native-tooltip-from-title-tooltip-text.
If you need to apply a custom class to the caption or input cells, you should be able to use the field's Caption cell CSS class and/or Control cell CSS class.