Don't guys normally wear something like that in old Japan days. It looks what I read in how to draw Kimono and Gowns.
4. As you reach the left side, tuck the twisted cloth under the strand on your buttocks, and go back, coiling it around the left part.6. Pull the apron under your legs, to the buttocks. Twist and coil it, this time around the right part.Getting started with fundoshi5. Form the apron1. Take the front part into your left hand and the rear part into your right hand, and put the cloth between your legs, so that both parts are roughly halves.2. Carefully set the front part in place, then start twisting the rear part, starting above your buttocks.3. Still twisting, gird your waist from right to left.7. It's done!
You can now get your brother or sister to check if it's been done properly.