Get back to the contours' layer and select the Pen Tool to finish representing the collar. Paint it with the basic color on a new layer situated lower than the previous one:

Miu Miu Anime Girl

Start painting it on the grouped layer (Brush Tool).

Miu Miu Anime Girl

Create now one more layer (a grouped one) and represent on it
 
white stripes:

Miu Miu Anime Girl

Blur them out, applying the next option: Filter – Blur – Motion Blur.

Miu Miu Anime Girl

Change the layer's Blending Mode on Overlay and combine the layers containing the collar's parts:

Miu Miu Anime Girl