So, there are several pieces that you would layer on. Pants are separate & shirt/robe is then crossed over chest/stomach and belted at the waist with the largest sash included. Then there are two other sashes that you drape over one shoulder, criss-cross and tuck into belt then drape over other shoulder and tuck into belt. So, from left shoulder across chest and back to right hip & right shoulder to left hip. Helpful Hint: I purchased small velcro strips to help keep sashes from falling off my shoulders. Lastly, fasten the decorative belt with buckle in front as pictured.

Is this like a jumpsuit all one piece?

A Top, Bottom, 2 sashes and a belt

need help, im 5'11 and weigh 150 what size is good ??

Wow! Quite a predicament. :) That's the problem with so many of these outfits. They're made mostly for tall thin people or for people of average height but extra roomy! That's been my experience. I'm 5'6 and am a weight lifter so I'm very stalky at 230 lbs. It's always a pain trying to find the right fit with these costumes. I bought the XXL and it fits perfect. Since you're thin yet tall, maybe you'd be OK with a Large. I'd bet the XL would be great in length but just too baggy. I guess it also depends on what kind of outfit you're putting together - cult, Jedi, wizard, etc. Go with a large.