I don't think you are in the wrong forum?
My advice would be to find a pro to model, take some lessons too if you can, and post a video so people can see what you are doing. I wouldn't pick Agassi. While he had a great backhand, it's not standard. He was unusual in that he hit with both arms straight. I'm not sure I've seen anyone else that does that. Typically, for a right hander, the men start with the right arm straight and the left arm bent, then as the swing progresses it switches and the left arm straightens just prior to impact and the right arm bends. Many of the women hit with both arms bent and frankly I have no idea why that is, or how they do that?
Djokovic is a good example, or Murray. Nishikori has a great backhand but I think his technique is more advanced and would be harder to model at first.