The best way to submit files electronically is to submit a directory containing all your project files. You must do this from a linux instructional machine.
If you are in section AA (9:30), and your current directory contains the directory "myproject" with the files you want to submit, then you would type:
turnin -c cse326=AA -p project2 myproject
Obviously, you must modify the above command to reflect your actual section and directory name. The argument following the -c flag indicates the course and section. The argument following the -p flag indicates the project number or code. (Use project2 for the B+Tree assignment). The last argument is the directory name. There is a man page for turnin on the instructional machines if you would like to learn about all the options, but it shouldn't be needed.
You should receive a message like "Your files have been submitted to cse326, project2 for grading". That's it. If you submit more than once, your latest submission will overwrite the prior submission.