Firstly you need to make a backing patch.
Repair a rip, tear or hole in fabrics that you cannot turn inside out
Some tips on backing patches. You are going to make your own from a fabric with a similar texture to the one you are repairing. The reason for this is to keep your fabric repair soft. It does not have to be from the same fabric that you are repairing. You could use an old piece of handkerchief / bed sheet. Etc. For silk or chiffon shirts and blouses use stockings, tights, net curtains, netting or a fine nylon fabric. Or if you are lucky enough you can use another piece of fabric from a concealed part of the garment.
Silicone paper is recommended here as the non-stick surface makes it easier to remove.
Place the Motif/Fabric/Backing patch onto a sheet of greaseproof/silicone paper.
Sprinkle with Supermend and place another sheet of greaseproof paper on top of your work.
Repair a rip, tear or hole in fabrics that you cannot turn inside out Melt the powder using a cotton/linen temperature iron regardless of the type of fabric you are working on. For delicate fabric use several layers of paper. Peel the paper back immediately before it sticks. If it does stick, reheat with the iron and remove the paper. Trim away any access glue or frayed edges.
Keeping the backing patch glue side up, Wedge and smooth flat between the lining and the top of the garment using a pair of scissors or a knitting needle. Put rips back together or fill hole with matching fabric. Cover with paper and press with a linen/cotton temperature iron regardless of fabric. For delicate materials, again use several layers of paper to prevent burning.
Supermend will melt to fix all the fibres together and the job is done.
All effective repairs can be washed boiled and dry-cleaned, over and over again.