Well, your AppleTV needs to be jailbroken first and it must have SSH installed in its system.
To those of you familiar with using sFTP to transfer files just like you can do with your iPhone, the connection and login details are as follows:
- Username: frontrow
- Password: frontrow
- Server: appletv.local (or whatever IP address your AppleTV is using)
- Protocol: sFTP (not FTP but sFTP!)
The first time you attempt to connect to your AppleTV, there will be a long wait up to 5-6 minutes. Be patient; your AppleTV is setting up access privileges for you. Subsequent connections would be much faster, although it’s slow compared to connecting to an iPhone.
 To find out the actual numeric IP address, go to Settings -> General -> Network -> IP Address