How to submit your solutions to AFS hand-in directory (AFS: Andrew File System)
Use a File Transfer Client, such as SSH Tectia File Trasfer (it can be downloaded from https://www.cmu.edu/computing/software/all/tectia/index.html. )
Connect to unix.andrew.cmu.edu and enter your userid and password.
You will now see your personal account on the remote AFS directory as shown below:
For the remote name, type in /afs/andrew.cmu.edu/course/24/681/handin-1 (or handin-2, handin-3), followed by your user-id directory as shown below.
Create a sub-directory as shown below:
Then, drag and drop necessary files from the left pane (local machine) to the right pane (remote AFS directory)