Picking a freelancer means selecting one freelancer from the several who applied for your Job. You can only do this after you have posted a job and received at least one bid
GO TO JOBS & SERVICES--> MY JOBS
Here You need to know 2 things.
1. "Bid Amount" for the Freelancer You want to pick
How much did the freelancer quote for your job?
2. Your Available balance
How Much Do You Have in your account. (You can Deposit More money Via Mpesa Paybill)
You need to have a balance that is equal to or more than the Bid Amount of the freelancer.