You can top up your account by clicking on "Balance".
Ideally, you would use a debit or credit card to make the transfer because this is instant. All you have to do is enter the card number, cvv, the card's expiration date, and the amount. We handle all card payments via Paypal's Braintree, so we do not have access to your card information.
Alternatively, you can also transfer money to our bank account or PayPal account, however this is not instant. It may take up to 2 business days for us to credit your Prolific account after a bank or PayPal transfer, but it's normally faster than that.