tax and shipping...how does this really work?

I am trying to set up my ning/cartfly shopping page and I have a question. Since I am unable to use my PayPal account, I have set up a new Amazon account through your prompts. i am a bit concerned about how to configure sales tax info for the state my company must report sales tax to which is Florida. I must charge any florida resident a sales tax rate per county. i was able to configure this with zip codes on PayPal but cannot find anywhere to do this on Amazon? I am a bit sketchy on how the entire thing works. Shipping is fine as I can use a flat rate through USPS, but do I just receive an email when someone makes a purchase and then I take it from there as far as setting up shipping? ANymore info would be appreciated.