You can submit one of your existing entries into a Challenge in one of two ways:
1. Go to the Challenge's page and use the "Enter Contest" button to select one of your existing entries.
2. Go to your Entry. Select Edit Entry --> Details and Attachments. From there, under the "Tag your entry" section, enter the contest's official hashtag (e.g. #qualcomm-robotics)
Note: You can find the Official Challenge hashtag on the Challenge's page.
To participate in the Challenge, your Entry must be viewable! Make sure to keep the Privacy settings to "Everyone"!