I've been playing around on Sibelius for a few years now (still only a sophomore in HS), and I have a few pieces I composed/arranged and I thought it'd be nice to get some feedback from people who know a lot more about composing than I do. I've never had any lessons on music theory/composing, so I'm lacking a lot of the "basics" in composing original songs. (My compositions are mostly based on pieces I've heard/played in my school band.) Any sort of advice/comments would be really helpful.
(I'm only arranging for fun, so I didn't pay much attention to instrument ranges...mostly just focused on getting ideas down)

Here's my latest composition/arrangement based on the "happy birthday" tune.
http://www.youtube.com/watch?v=b8UoS0bQ6jM

And here's one where I tried to write music to go with a video.
http://www.youtube.com/watch?v=5HP0fiDNiDw

thanks.

I like both of your compositions. They're fabulous for being made in sibelius, not with real instruments. Great job! Your percussion in Years is great, and you did a good job at covering up happy birthday. I enjoyed both, keep it up!

Excellent! I enjoyed both very much, especially the sound track for the video. Good cartoon too and the music does wonders for it.

I think the video is adorable, and the accompanying music fits it perfectly and embodies that...clean, simply textured, and with quirky and effective themes that are developed subtley, with a kind of melodic happy and lyrical innocence, which fits the story exactly. I really loved it...put a smile on my face :)Thanks for sharing

Nicely done. You could be making money already writing title music for TV programs. The first one sounds like an intro (up to the first 48 seconds) to some expose news type program.