Beginners can usually improve their performance if they work on a smoother pedal stroke. A smoother stroke should allow you to pedal easily at a higher cadence. A cadence meter will tell you how fast you are pedalling, but you need to figure out for yourself how smoothly you are pedalling. If you think you are pedalling smoothly (knees don't twist or wobble, hips don't rock) and your cadence meter says your cadence is good (around 80-100 rpm), then you are doing well.

As you develop a strong base form, you shouldn't have to worry about cadence on flat roads anymore. You can still use it to keep your cadence up when climbing. Even Lance Armstrong says he still uses a cadence meter when he is training for mountain climbs.