Write a Contract for Pay Per Time Projects

I have legal business established in Serbia. My company provide services of custom software and web development. Big part of my income is coming try websites like upWork and Freelancer . I need template for PAY PER TIME CONTRACTS. for work witch will be done try upWork. In this template i must have full identification of client. Contract number, contract name, and it must be clear that work will be done try upwork. you can find samples of some contracts used for [login to view URL] hire [login to view URL] but i dont see pay per time contract.