Well...none of those details really help, except maybe the wide barrel part, and even then, not all wide horses take a wide tree. This video on fitting is pretty clear-cut... http://www.videojug.com/film/how-to-fit-a-saddle
You also need to decide what kind of saddle you want. From what you've said in the past (low-level jumping), I would recommend an all-purpose. Good for jumping, but still comfortable enough to take on the trail if you're so inclined, or do low level dressage in. If you have any more specific questions, it might be easier to help.