Place objects in a straight line

Yes, I found that my original problem was having multiple straight lines in a single group. When I put each line in its own group it came out fine. The only problem was the alignment of things. I had to move one of the lines around to get the bushes to align the way I wanted them. You can see that in the image I included.

I sometimes do still have some problems trying to specify the density (especially in my straight line example). Is there someplace else I can read/watch to understand how to be more precise?

I will send the later today.