If you are using MX, there would be a lot of documentation about flash +serverside scripts (PHP, JSP, ASP).
But I it is best to have a good basic knowledge about programming first (variables, statementes, loops and so on)
A good beginner book about PHP is "Core PHP Programming" by Leon Atkinson.
It also covers some of the basic concepts in programming.
It s also a good reference for more experienced PHP programmers.
Have not red any Flash books yet 🙂
If you have access to a web server, try start with playing around with loadVariables() in flash (see the help manual)
www.flashkit.com is a good resource.
regards
Thomas Andersen