This is just a further f.y.i. and for anyone else that might stumble upon this discussion thread.. as the question does get asked frequently by those unfamiliar:
'Cutting to the chase and to answer your question..
Yes, upload first.
*Then, once approved it should appear in the drop-down menu (at the top of the "Contest Topic Poll" page beside "Enter the contest" button) for you to choose whichever image to submit as an entry to the contest.