Transfering files using sockets

hi there all...

I would like to have some more information on transfering files using the socket class

I have seen some documentation on sending files with socket.sendfile or socket.beginsendfile (async and sync)

so i do have a few questions about those things

1: why would i want to choose sync over async or visa versa?
2: how would i go over saving the sent file on the other side?

i would just like to know the best way to send over files.

please help soon, i need it for school...

thanks!

-Rayko