Incorporating my images into designs

I've discovered the "reference image" feature. You upload your own image, type in a command, and Firefly spits out an image that is somehow patterned after the image you uploaded.

For example, I uploaded a picture of a flag and asked for a "flag waving in a breeze." It created pictures of generic flags with various landscapes in the background.

However, I would like to create pictures featuring MY flag. Is there a way to upload images not as reference items but as elements of a picture you want to create?

Ideally, I would like to create some images of various flag designs flapping in the breeze, with no background at all. I can then add various backgrouns later.

Thanks.