I am a new one in forum posting area and i dont know how one can withdrew money from a paid forum posting.
most of the service buyers use PayPal for paying agreed amount. if you do not have a PayPal account then you need to register in it.
Main purpose of forum posting it participate the discussion and sharing the ideas. At the freelancer view providing the back link to hiring manager. To earn from forum posting login to different market place like microworkers, odesk,freelance site and perform job and get paid.
Odd question... shouldn't you be asking the person who has employed you to post? It depends on how they are paying you. If its a regular company and you work in their offices it will be very different from if you are employed via the Buy/Sell/Trade forums here or some other website.