Prepare the soil in your vegetable garden in a row on the northern edge of the plot.
Dig holes for support posts every 4 to 6 feet along the length of the row. Make the hole at least 2 feet deep using a post hole digger.
Insert a support post in each hole and backfill with soil, firming it down with the scrap piece of lumber as you go. The poles don't have to be perfectly plumb, but they should be as straight vertically as you can get them.
Staple concrete reinforcing wire to the posts using a heavy duty staple gun. Attach the bottom edge of the reinforcing wire to the posts a couple of inches above the surface of the soil. The reinforcing wire can extend for a couple of inches above the tops of the posts, if necessary.
Plant bean seeds 1 inch apart all along the length of the trellis. Thin so they stand 2 to 3 inches apart when they germinate in seven to 10 days.