Each site mentioned has a short review for you to know what the site is and an overview of how the site works. You can opt to post your jobs/projects and wait for service providers to bid on them. The article has a posting guidelines that might help you when you post your jobs/projects. The article also speaks of a few guidelines when hiring someone offshore so you will be effective in the process. It's always annoying and a waste of time when service providers will just leave you even if the project is not yet done.