I am new to submitting and my Thumbnail got squished...

How can I submit a square version to fix the one on there now?

I believe it has to be 502 x 502. Can’t fix once posted, but you can cancel and resubmit.

Actually it’s a 602x602 gif, jpg or png for the shirt comp and 186px186p gif, jpg or png for the design detail. It says so on the derby submission page when you click “What’s this?” beneath the upload fields.