Newbie questions

Hello group :+)
I have this passion about learning to fly-fish - I'm fifty-two, and
really need this for various reasons. I decided to begin slowly and
inexpensively, in case I find it impossible (and I'm poor), so I
bought the cheapest rod/reel outfit at Wal-Mart. Now ANY help is
greatly appreciated!
What is a "leader"? What type of line should I get? Any good books out
there? I have some flies I bought on Ebay, and a vest, but what else?
A net, waders?
How much should I spend on this stuff? I want to take my wife and two
daughters, but the girls are too young - four and nine years old...I
want them to remember this, and to experience it themselves...
I'll probably fish in North Georgia, as I live outside Atlanta...I've
checked out some good websites, and there is year-round fishing in
most of these counties...
I can't afford lessons, guides, trips to Montana, etc....
Please don't tell me to take up golf, or to go catfish/bass fishing...
any advice is really appreciated - THANKS!! Paul