Hope you've got a programmer you can consult with to see if the people you employ have genuine skills or "made up web skills". There are way more of the latter doing the rounds on the freelance websites.
This should be the concern.
Now, someone wouldn't necessarily need to be a full blow programmer to commision this project, but the specs presented in this thread suggest the person soliciting help for this project probably ought not be the person running this project.
This books on practical programming exercises might get the OP up to speed though.
I don't think the OP wants (or needs) to learn how to program. He needs help from a web programmer in helping choose a developer.