In an ideal world you would use a free-standing embroidery frame, but they are expensive and take up space when not in use.
You could try the method used for silk painting: attach the fabric, stretched reasonably taughtly, round an old picture frame or else a 'picture frame' cut out of a cardboard box.
You can get special pin grips (like little metal cat's paws) for silk work, but I expect you could fettle it with some straight pins.