You can do it in one of two ways:

1) In the menu, there is the option to upload funds. You simply select how much you would like to upload and then authenticate the instantEFT transaction provided by EFTSecure.

2) When making a transfer, if the amount that you would like to send is more than your balance, you will be asked to add funds either using Bank Card or instantEFT. 

If you would like to pay using a credit card you will need to add a card first and undergo a simple but essential 3DSecure verification process.