sharing a folder with my friend

Hello Dear!!!

I have a P.C at home with Extrnal Modem. and My friend also has P.C at home with Internal Modem installed in it we both want to share our one folder to each other. We already share our folders by right click and select share. But wedont know how to negotiate our pc each other browse other folder.

Secondly can we share our folder on Internet too. If yes the how it is possible

Advice me

thanks

Nadeem