You need to get Flash installed. Get Flash it here.
Practice these strumming patterns on a single chord that you can play comfortably. Once this becomes easy for you, try different chords, and if you are ready for it, see if you can switch chords after each measure.
Keep in mind it takes a little while to get the "feel" of strumming. At first, it will probably feel, and sound rough. Just stay relaxed, and keep practicing !