How do you submit completed programs? I've tried the instructions sending you to Chrome
Using chrome in your browser, go to the following link and login using your EdX credentials.
Mouse over the top left hand corner of the page where it says "CS50x" and a drop-down should appear.
On the left hand side, choose the appropriate pset.
On the right hand side of the page, choose "Upload Submission" and follow the instructions given in the pset guide. Usually you click "Add files", choose the appropriate files from your dropbox folder, and then click "Start Upload". Once the upload completes, you are done.