Step 1:

When you click on "submit", you should be able to see "Submit Programming Assignment" prompt as follows:

Step 2:

Please click on "Click to Browse" button. A file manager will appear. Now, select ALL the files you want to upload. In case of MP2, you would select both perceptron.py and neuralnet.py.

Step 3:

Alternatively, you can also upload one file at a time by clicking on "Browse Files" button as shown in image below. Once you add both the required files, click "Upload".