Problem to determine suitability of a person willing to offer as I must pay first

Questionable service that is offered by peopleperhour. I have found no way of checking a persons credibility  or experience before I pay! I could potentially have used a person that sent me some information about his skills but I needed a bit more information. I certainly will not pay before I know if someone is likely to be able to do the job! Unless I have got this wrong please let me know what to do by return mail. If I do not hear anything within one week I will look somewhere else for help and block all mails from peopleperhour.

Bjorn