Step #1: PrevNext
Select a flat, level location in full sun (if growing tomatoes). Clear out any debris. Measure the length and width to suit your particular space (ours is 8 feet by 3 feet) then mark the four corners with gypsum or other powder. Our trellis required a third vertical post, so we marked the midpoint on each long side with more dots of powder. You will now have the outline of your trellis and the points where posts will go. Note: You can change the size of the trellis to suit your needs, but be sure to have your lumber cut accordingly.
Step #2: PrevNext
Loosen the soil where dots are marked with a sharp shovel to a depth of 1 foot for each of the six posts. Using a mallet -- or even a large rock -- pound the vertical posts into the ground. Measure 1 foot down from the top of each vertical post, and then tie opposite sides together to make three teepee shapes.
Step #3: PrevNext
step 2 With strong twine and sturdy knots, tie the horizontal rails at 2-foot intervals on each side of vertical posts. Snuggle the remaining horizontal post into the crossed pieces at the top of the trellis, and secure. (We added screw-on wooden finials for a final flourish.)