Changing postage charge for individual buyers

[fluffyanimal]

Hi, can anyone tell me how to charge a different postage rate for an individual buyer? Someone has contacted me to ask if I will ship overseas, I'm happy to do it if I can charge the right amount of postage, but don't know how to change it for that buyer.

edit the listing and add the postage in the little boxes for overseas (europe and worldwide)

or you can amend the final invoice after they have won the item.