Custom Fencing/Fence Panel?

[DRob106]

Hi All - I'm using Home Designer Pro and I need some help to customize fencing such that each panel consists of:

6' 4x4 posts every 8 ft (Figured it out while playing with object properties)
6" x 1.25" Top Rail (Figured it out)

16' x 6" x 1.25" horizontal "pickets" spaced 1.25" apart, evenly distributed vertically across the posts.  (Can't figure this one out)

1"x4"x6' vertical boards to cover the seams at the center marks of the posts

Any help is greatly appreciated in advance (and possibly afterward as well...  )