Now there are many sites for freelancers, such as Toptal, Upwork, Fiverr and others. If you have a desire to create your own site, you need to study this issue very well or ask professional developers.
Technical progress does not stand on one place. There are a lot of trading platforms for freelancers, so in order to implement your own freelance marketplace platform , you need to carefully study this issue and learn the information, which is a pretty decent and effective solution, which describes the most effective opportunities on how to develop it, tips and analysis of the correct operation of the business. I think it's really easy to implement with this kind of help.