After you've submitted a request, and have received a quote you are happy with, here is how to hire the service provider.
At the bottom of the request, click on ‘Hire This Pro’. The same option is available at the top-right portion of the bid. Once you have done this, the service provider will be automatically notified via email.
The request will then be marked as hired and you will be prompted to leave them a review (or you can choose when to be reminded):
After you have hired the service professional, you can still communicate with them through the 'Your Requests' page: