I think I've got the hang of this now. The weather has been awful, so another day in the crafting studio, aka my living room. I haven't got one of those wooden embroidery hoops so a bit of imagination was needed to find something else which would do the job. Take one wooden picture frame, remove the backing, picture, and glass. Then stretch the fabric and net over it and secure around the edges with plastic clips. I used a piece of curtain lining fabric for the first practice piece.
The mesh is removed. These stars are quite tiny and not all exactly the same. I don't think it matters.
The second one I did was on a piece of orange silk, using two colours of cotton. The silk was slipping a bit and I had to adjust the clips as I was working on it. Some of the lines are a bit wavy. It would probably be better to use a hoop for slippery fabrics, to stop it moving about.