Hi,

well, the worst that you can do is just write a job offer for "a clone of site xy.com". Better is if you make a detailed list of features that the programmer can work with.

Write everything down that you want, what you want the user experience to be like etc. Be sure to describe everything as detailed as possible. I think that a good programmer should then be able to help you formalize everything and make a feature list out of it. Then you can go and set milestones and iterations, define when what features should be done, assign priorities etc.

Also, you might need a separate designer who creates graphics etc. But you can hire those two guys separately. I think there are few programmers who are good designers and vice versa.

That's how a proper software is being developed. I can guarantee you that you won't be satisfied if you just order a clone. So to make it short: "Best describe what you want, as if the other site wasn't there already."