The music was, on the whole, solid for pop music. You're basically using the same four chord progression over and over, so your only option is to get more and more elaborate with your right hand figuration (which you did, accelerating with smaller note values, and then moving on to thirds). Your next task should be writing something like this, but having a "middle" section with a different chord progression. This will make it feel as if there's more going on, and if you can connect the middle section back to the original chord progression, then there will be more excitement in returning to the original progression. Also, the ending came off a bit quizzical. Why did you end it on that chord? It feels as if you tried to make up for a lack of a cadence with a flourish down the keyboard.
What I would recommend would be to play some classical pieces. What chords are they using? How do the melodies relate to the chords, and how do they lead to the next chord? An introductory book on harmony would also be helpful, but really, it depends on what sort of music you're trying to make. If you want to make pop music, it might be helpful to study artists who you respect or whose sound you would, at first, like to emulate.
Topic: original composition