Tell me any file transfer program to transfer files over Internet to my friend

Please tell the sysop of your friend and if your friend has a static ip...

FTP protocol (which is used by Filezilla) is a classical solution. You could have to configure router of FTP server for incoming traffic. Don't forget to set a password.

The best way is to configure your computer as a file server; this can be done by installing an FTP program, as suggested by delance.

You could install the "proftpd" program, and use that, for example. Then you can configure it such that certain folders are acesssible by typing

ftp://YOURIPADDRESS/path/to/file

into either a browser, or an FTP client (better) and the file can be downloaded.

to get your IP address, you would need to either look on your router's configuration page, or use an online service which tells you.

I know that we can transfer file across internet using FTP protocol( I have been using FileZilla to upload files to web servers), but I dont know how to configure my PC as a file server(or FTP Server).
Please help me with this by giving me some detailed steps.
I know how to identify my ip address( www.whatismyip.com shows our system's ip address, I hope i'm correct if not please correct me).
I also downloaded proftpd program few days ago and tried to configure it by giving my ip address and creating a user and adjusting the settings but it didn't work.
Then what to do?

Thanks for your replies.

http://www.ubuntugeek.com/settingup-an-ftp-server-on-ubuntu-with-proftpd.html

Before you try to access it externally, check that you can access it on the local computer using the special "localhost" address (aka 127.0.0.1). If this does not work, then the external definitely won't. However it is possible for this to work and the external IP not to work if you have not set up port forwarding on your router correctly.

Thanks Andree Wille, that solved my question.

Thanks for all of you for your help.