Just make the payment or send money to others. When you pay, the amount will be deducted from your PayPal account that you add to Paypal (if it's not enough in your PayPal account). I don't think you can add money from Debit Card to PayPal though.
Yes you can send payment using debit card (Visa or MasterCard)if you country is listed here https://www.paypal.com/us/cgi-bin/webscr?cmd=_display-approved-signup-countries-outside https://personal.paypal.com/us/cgi-bin/?cmd=_render-content&content_ID=marketing_us/debit_card