I'll point you to: http://fedex.com/us/developer/product/resources.html
That's their web API. They even offer PHP downloads & release notes. Just read them and you should be able to do what you want. You should* be able to do what you want for free.
* This may not be the case. You may be limited to the number of requests, or they may out-right charge you. Research costs before doing anything.