If you have never registered before:
Go to: https://deewhyfcacademy.myclubmate.com.au/myDetails/ 
Click on the 'register a new player' tab and follow the instructions.  It will ask you for what age group the player should be registered. This is where a list of the classes that are avaialble are. Please select the class you would like.
If you have already registered and now need to sign up for another class:
Go to: https://deewhyfcacademy.myclubmate.com.au/myDetails/
Log in using your username and password. Then click 'Add New Player'. Enter the exact same details you have already entered previously. This basically allows you to add another class for that player. (See image 'step 1' above)
Once you have entered all of the details, then click the drop down 'age group' box and select the new class you would like. (See image 'step 2' above)