A few helpful hints to help you get started.
Join a flyfishing club. Go to http://www.clubsofaustralia.com.au/ and find a fly fishing club near you. Attending the first few meetings can be intimidating, so go introduce yourself to a woman in the group to break the ice. Or take a friend with you to the meeting.
Identify women guides. When you want to go flyfishing just call around to flyfishing guide services and ask if they have a woman guide available. Then patronize those that do.
Get lists of registered or licensed guides from your state department of fish & game or call and ask if they know of women's programs. Also ask if they sponsor a Woman Outdoors program, which are being offered in more and more states. Most such programs include flyfishing as one of the workshops they offer.
Get out on the water and look around for women that you see flyfishing. Introduce yourself and ask them how they got started or if they know of resources you can use.
Organize your own class and hire a woman from a nearby area to come in and lead it if there are no resources in your area.
Attend an outdoor or sports show that includes workshops or demonstrations on flyfishing or casting clinics. Try to make contacts there to learn about resources either in your area or within a reasonable distance of where you live.
And if nothing else is available, check out some videos or books from the library or rent them from shops that sell flyfishing equipment.