QuickTender is an ewallet similar to Neteller or PayPal.
You are only allowed to have an account if you are invited by a casino. If you'd like an account, ask InetBet and they will set you up.
You can deposit to your QuickTender account with a credit card or bank account like you would a PayPal/Neteller account. You then use your QuickTender account to deposit (and withdraw) from online casinos.