Thanks for the plug, Diogenes! Here's a clickable link for easier access: http://www.aaronofmpls.com/lc/. (BB Code and simple HTML both work in this forum. For examples, click the "bb code" link at the top of the message box.)
Like Diogenes and Haraak said, there are many different styles around the world, from simple breechcloths, to Japanese fundoshi, to the Roman subligaculum, to wraparound tied styles from Polynesia to the Philippines to southeast Asia to Mexico and Central America. Materials vary just as much, from leather, to bark cloth, to knit cloth, to woven cloth.
Myself, I mostly wear this kind, which wraps around my waist and between my legs, and is tied in back. But I have a few breechcloths too, which fit better under other clothes.
I prefer soft but stretchy fabric -- cotton lycra if I can find it. But use whatever feels comfortable to you, and fits your budget and style. There is no one "right way"!
(Tip: For straight edges, woven fabric can be easily torn in a long, straight line if you make a small cut at one end. And many knit fabrics have visible "ribs" running the length of the material, which you can cut along if you're careful. Look closely at a t-shirt to see what I mean.)
thanks for the messages. i understand a breechcloth is held up by a belt of sorts. i was thinking of something not like this, rather something that wraps around and secures itself.
Here's an idea. Look up FUNDOSHI on Ebay. I've bought several from Fundoshi Taro. The Rokushaku is one long piece of cloth and secures itself. I have photos of me wearing Fundoshi on my Tumblr, as well as other types: https://native-loincloth.tumblr.com/