If you want to charge on your magic band, the resort will place a $100 hold on your file (credit card). And each time you reach or use $100, another $100 hold. While holds are not charges, it does take up to several days for your credit card to remove hold. Thus, less amount on your available credit.
When you are done eating, whether on dining plan or not, you will receive a receipt. The receipt will have dollar amount (If on dining plan, cost of what meal would have been) showing credit used. There is a line for tips, simply fill in the amount you would like to leave, place it with the gift card into "folder". Sit back and wait, receipt along with gift card will be brought back to you. You will then receive a gift card receipt showing your transaction, with remaining balance.