You can find a freelancer by clicking on "Find a freelancer" from the menu. Then choose the job category to find a freelancer who knows specific skills.
You can also access it from your profile
Once you find people you would like to work with, you can send them a message by clicking on the "send job invitation" button. Then you will get to the form to provide more details about the job.
You can read more about inviting freelancers to work together here.