Now it's time to start the real fun. When you try Arcade Mode (Free Play Mode in DDR Extreme 2)for the first time, don't overdo it. Try a song that sounds good to you, but make sure to check how hard it is. Look for a little grid in the corner, kind of like a graph, but with 5 different axies: chaos, air, stream, freeze, and voltage (Some mixes don't have this). Chaos is the number of offbeat steps, stream is the number of steps in a row, air is the number of jumps, freeze is the number of freeze arrows (Arrows you hold your foot on), and voltage is the highest number of steps in a measure. The farther to the edge of the axis they are, the harder the song is. There is also a foot rating from 1-10 (Sometimes a flashing 10), which is usually a summary of the 5 difficulty criteria. As a first time, you might not want to do a very hard song. You shouldn't do anything higher than a 4-foot basic song on your first time playing. Step on the arrows when they reach the arrow bar on the top of the screen. The arrows are usually to the beat, so be sure to listen for it in the music. This is dancing game, and you should try to dance, or at least enjoy the music. Lose yourself in the music, and you will feel when you need to hit each step, and with which foot (This will become important later). The more work your head does trying to decipher timing, the harder a song will feel. If this doesn't suit you, however, you can play however you want. Develop your own style (Or use this one) and get practicing!
Another important point I would like to stress is DO NOT STAND IN THE MIDDLE! I have seen so many people doing this. By standing in the middle, you limit your mobility, tire yourself out, and look silly. Move from arrow to arrow; the middle is a placeholder. Make your movements seem more fluid, rather than clunky steps in the middle.