I use iron on inter lining to protect the back of my embroidery work. I do this because I’m using it as a bag and don't want anything I put in my bag to get stuck in the backing of my embroidery work. If you use your embroidery work simply to display, this is not necessary.

I simply cut a piece of iron on inter lining a little bigger than my embroidery work. I cover the back of my embroidery work and simply iron it on.
To protect the iron I put a piece of fabric in between the iron and the inter lining (sometimes the iron can get dirty/sticky from the interlining).

I don't like to slide over my work I place the iron from place to place. When I sew the bag together the edges will be concealed in the seam.