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.
The My Profit and Loss page is available in the Betting Activity section of My Account and reflects your returns minus your stakes for all bets settled within the chosen date range of 7 days, 30 days, 3 months or 12 months (including any bets placed outside the date range but settled within it).