"A yukata (浴衣?) is a Japanese garment, a casual summer kimono usually made of cotton or synthetic fabric, and unlined. Yukata are worn by men and women. Like other forms of traditional Japanese clothing, yukata are made with straight seams and wide sleeves."
Comparing with colourful women's YUKATA, men's are totally SHIBUI (Japanese words which refer to a particular aesthetic of simple, subtle, and unobtrusive beauty. by wikipedia)
Here is some good youtube and web site "How to put on YUKATA"