Press again for ten seconds, just for good measure. A little trial and error will make you an expert. For example, you will want to use the part of your iron where there are no steam holes. If you have a problem with steam holes showing you may want to use a teflon pressing cloth. Everyone that sees this fabric has to touch it and then wants it for pillows, clothing, drapes, and more.
Random design is easy and forgiving.
You cannot correct your mistakes, so do not set yourself up for disappointment. For instance, avoid a perfect border. Cut out your pattern and then emboss. If you are embossing a garment like a jacket, you should pay attention to placement- there were two spots on the front of a jacket I did not want the design to land on. I might get more attention than I bargained for.