Like others have mentioned, the story is pretty cliched. The inexplicable powers Harry one day wakes up with, the betrayal, manipulation, etc. Hopefully that the cliches will only be in the beginning so that you can take the story somewhere original.
Longer chapters would be better as the reader would be able to get more into the story without the sudden cut-offs after 900 words. I would say to go for 2500 words as a minimum goal.
Other than that I think you're doing alright for a beginner, that's what this is all about, isn't it?