To place a Quaddie bet, select your race and the Quaddie tab, make your selections for each race, and add them to your bet slip. Enter your stake and click "Place Bet." If there's a scratching, your bet is recalculated with the substitute declared by the Victorian TAB. If you've already selected the favorite and it wins, you'll be paid double if the rest of your Quaddie wins.
Step by step:
Select the race you'd like to place a Quaddie on.
Select the Quaddie tab.
Make your selections in each race.
Click add to bet slip.
Enter in the amount you'd like to place your Quaddie.
Click Place Bet.
When there's a scratching in your quaddie, your bet gets recalculated with the substitute declared by the Victorian TAB. If you've already got the favourite in your quaddie, if the favourite goes on to win, you'll be paid double if the rest of the quaddie goes on to win.