After you download the assignment you pause the PearsonVUE test.
This puts the test in a state where you see the "Continue" button and the number of days you have to upload your solution, ie 6 mnths since download.
When you are ready to submit the assignment, you jar it up, carefully follow the instructions in your assignemnt pdf to create the jar.
Log into your PearsonVUE account, and hit teh continue button. Then click next, this will display a file upload field.
Upload the jar and follow instructions on screen.
After sucessful upload, you will see a message suggesting that you to register for Part 3.
They dont grade your test unless both Part 2 and Part 3 are submitted.
To the best of my belief, you have to submit Part 2 and 3 within 6 months of assignment download.
Hope this helps.
SCJP 5.0, SCBCD 5.0
Working towards OCMJEA, cleared part 1,2 and 3. Yet to attend training