To the right of each payment method field is a text box where you may optionally enter "special instructions". They will be shown to the customer during checkout and can be used to pass along important information to the customer. Example: "Make all checks payable to...".
The next section is used to allow customers to purchase from your store using their PayPal account. If you want to allow this type of payment during checkout, please "activate" PayPal below and complete all of the fields.