This is a re-post from last year with some added material.
Once you drive the 3/4" conduit into the ground with the fence post driver, you'll want to cut the top to your desired height with a tubing cutter(for metal tubing see the pics above, which you spin and tighten to make the wheel cut deeper each revolution). The fencepost driver can sometimes make the top of the pipe "mushroom" a bit. In any case you'll need to use a ladder to work with the top of the "posts". Otherwise you'll have a terrible time trying to drill the pilot hole for mounting 1/2" X 5' top.
These become part of your garden's "permanent bones" so install these only where you want them present for many years. I have a line of 3 of them along the east edge of both 16' long veggie beds and a pair of them on the south side of our brick home to grow self seeding morning glories to shade the wall. I think it saves a bit on the air conditioning bills. The latter are full 8' height trellises.