Excellent debut!
Really nice progression with a minimum of frills there. Of course, it's not exactly front-line-of-battle music, but it's not any worse for that. I think that you're really good at just sticking to the basics and crafting a simple, but very effective piece.
I won't make any suggestions for percussion or other "more exciting" instruments that some other people will undoubtedly make - I really don't think that this piece needs anything more than what it has.
I look forward to your future submissions!