1. the harness thickness when i turn any number, it is still o thickness? why? i don understand
The garment has to be in render thickness mode in order to see thickness.
Keep in mind, the thickness doesn´t export. It´s only a rendering trick, it´s not actual geometry.
2. in the vedio the zipper the polygon didn´t create dart how come the zipper hole can see through???
is it because of the file format? .png???
Yes, you can use images with transparency.