Welcome to the world of photography! I myself am a beginner and use Picasa sometimes. You should also give the photo some contrast and shadow, you can do this in Picasa. Use the auto contrast button and slide the shadow bar until you get some depth in your photo. I don't like to use the glow as it removes focus and makes your photo soft (it works well on face close up but not much else). Hope this helps! Good luck in your journey!

Thanks for the tips!

BTW, you can edit your photo and resubmit it. Just go to My Stuff then to My Contest Entries under the photo click edit entry and upload your edited one. Be sure to check the hi-res at the bottom of the page.

I entered too late to win anyway but thank you SO much for all the tips!!

Welcome, I quite agree with rbsgrl, and it's not too late to change the photo, uploading doesn't finish until the end of the week.
You could also consider re-shooting, there is something about the composition that bothers me. Think about the flowerpot being it's side and the writing which is very appropriate is a little disconcerting being upside down.
good Luck

I agree with the comments above. There's just not enough color in the banana.