Use your hammer to drive a stake 2 inches into the ground. You'll need one stake for every cucumber you want to grow in your plot. Connect your garden string to the top of one of the poles, and then run it along the tops of your other stakes, all the way to the end.
Put a short stick into the soil, a couple inches away from each stake. Tie a piece of string to the one running along to the top, so it drops to the soil and then ties to the stick. You'll need a piece of string for each cucumber.
Untie the string from the shorter stick and attach it to the cucumber when it emerges from the soil. Shorten the string as the cucumber grows, to train it to grow straight up.