Some plants needs an extra support to grow tall. Peas and Beans are an example of these kind of plants. Trellis structures can be as simple as a wooden stakes or as intricate as interwoven lattice. Plants are trained on a trellis to conserve space, increase light penetration into the plant, display the plants and fruits in an interesting way, improve air circulation, reduce desease, and ease harvesting. Set a stake at the same time that the plant goes into the ground and loosely tether the plant to the stake with a soft tie to keep it from toppling or being demaged by strong wind.
I just built some trellises for my peas in my garden and I used bamboo stakes and some string, it was really easy. Infact peas are very easy to grow and they will crawle up pretty much anything. For beans a tepee style trellis is very common and also very easy to build