Let me break it down for you:
When the brain processes visual information, it processes it time and spatially oriented. Like looking at a painting. You see the time of day, and the points closest to you and most important first. That is the way syntax in ASL is arranged.
When the brain processes auditory information, it does it in a linear way. Like saying, The boy climbed the tree.
If you were going to say the same thing in ASL, or if you were going to paint a picture, the tree would come first, because without the tree, the boy wouldn't be doing anything.
Is that better, or more confusing?