Those pics are very nice! I enjoy photography too but I only have a little Canon Powershot A570 to work with. If you want to learn more, there are lots of online photography lessons or advice that is basically free. This is one website that offers some cool advice
Digital Photography School - Digital Photography Tips for You.
If you want to photograph for other people I would advise upgrading to a better camera for better quality pictures.
I'm not a professional but I think your pictures are really good! Maybe Equine Photographer can give you more of a professional's point of view.
