In summary, to make money money on Betfair you MUST do two things. First, suck up every bit of knowledge that is available. Build up a small list of 'edges' to deploy when the time is right, understand that each of them has their place. However, the Betfair markets dictate when you will be able to use them.
On browser you can access the withdrawals page by selecting 'My Account' in the top right and then 'My Betfair Account': From the following page, a 'Withdraw Funds' button is present on the right-hand side. If you are able to withdraw this will be green. If you are not, this will be greyed out.