Help: Issue with changing image to halftone with transparency backgroung

[Zodiak1970]

I was following along with a YouTube tutorial on converting a photo into halftones.
I followed step by step however when I completed the steps I still had a white background (after inverting color for black tshirt) the tutorial showed the exact image as I had however the background was transparent (checkerboard) I'm so frustrated I understand gimp has a learning curve it's just discouraging on what is a fairly simple thing as this to keep finding yourself not accomplishing what seems simple.