Knit hats

I am not a knitter, but I do sew and I am making fleece hats for my grandson and am wondering on how to go about making a tassel for the top of it out of yarn. My mother used to knit hats and had these tassel (balls of yarn) on top of the hats and now I would like to add them to my hats. Can anyone help me? Thank You in advance.

Is this what you were thinking about?

Or this?