How do I change my model to work properly with UV Unwrap? I created a character and now I want to texture it.

It was going well until I tried to add texture on sunglasses.

I open the UV Image Editor, after I unwraped the sunglasses and I am getting only a dot. Please take a look as shown in the picture below:
Try to add the mark seam on your sunglasses, Please select the boundary edges one by one and than 

Follow the menu as shown in image 



Or hit Ctrl + E and select the Mark Seam from the menu.

After adding Mark seams, Please Unwrap again, Good luck :)