Yes! You need an active StarPass to submit designs. Submissions are done through the Creator Studio on the web version of Everskies.
How to Submit a Design:
In the Creator Studio, click "Create new design."
Upload your item, position it on the avatar, and give it a name and tags.
Go to "Publish," set the price, agree to the rules, and submit.
Your design will be reviewed by other creators, which usually takes up to 14 business days. Please be patient and don't resubmit your design, as this will reset the review process.