It definately shows potential.
First of all, why did you choose Clarinet in E Flat? You put the song in C Major, so a Clarinet in B Flat would've been a better choice, as the player would have less sharps to play, and so it would be more comfortable.
Secondly, while Finale has a pretty decent soundfont, for some reason the volumes are a bit off, for the trumpet in particular. When I still used that soundfont, I always had to turn the trumpet down a lot. The clarinets and french horns, too. And the strings always seemed extremely quiet, so I had to turn them up a lot. Also, you have Finale setting your speaker balances for you. (i.e. Flute is towards the left, and trumpet is towards the middle. This will naturally make the trumpet louder.) So that will solve your problem there.
As for where to go next, I don't know. I can hear it going in several different directions. You're definately off to a good start though. In particular I seem to hear a flute solo, with maybe some chords played by the celli or trombone.
It might not be a bad idea to add a French Horn part as well, as it blends very well with the other families, and so you can easily use the horns as a bridge inbetween parts of a song.