For anyone interested in learning to enamel I can highly recommend this book by Dorothy Cockrell. She is a longstanding member of the Guild of Enamellers and editor of the Guild’s quarterly journal. She writes in a very clear, no-nonsense style and this is a well illustrated book, with plenty of projects to get you started.
I would also recommend you to join the Guild even as a complete beginner, as joining will bring you into contact with such an enthusiastic bunch of people, generously willing to share their knowledge at regional meetings and other Guild events. A number of members run classes, often aimed at beginners and at introductory level. If you would like any further information then either have a look at the Guild website or email me.