Go to the Services tab and find the Changelly Instant Exchange link. Open it.
Changelly allows you to instantly buy XEM from inside the NanoWallet using common payment services like Visa and Mastercard.
First choose the currency you wish to use from the drop-down menu. Then hit exchange.
Changelly will give you instructions on how to complete the transaction and the XEM will arrive in your NanoWallet as soon as the transaction is verified.