It "should" be possible, you have to know your IP and give it to your brother. It is easier if you give your IP a name:

www.no-ip.com

Your brother have only to know this name while you are running no-ip.

I would suggest you a ftp server for private sharing. Its easier to find you can allow other files to download, you know that only allowed people can download this files (password) and the people who download have your full bandwidth.

Morgwen