Plants can be a bit tricky.
First of all, you need enough light for the plants to grow, and different plants need different light levels. Then you also have to plan on a time period for the lights to be on. And if the tank gets too much light, you can start having issues with alge growing faster than the plants.
If you want to start "playing" with plants, simply replace your existing incandescent light bulbs with CFL light bulbs. You want bulbs with a high color temperature (Daylight with color temperatures around 5000K to 6500K, NOT Softwhite or Coolwhite with color temperatures around 2700K to 2500K). Start with a CFL of equal comparable wattage, as time goes, you may find you need to try a higher or lower wattage bulb and you might need it on for longer or shorter time periods each day.
Get a timer so the lights will go on/off automatically, unless you can be religious about turning the lights on/off. (That's one of the thing I hate about these day/time night/time (moon light) light sets, you can't plug them into a standard timer and get your daytime/nighttime light switch over).