I realized it
Check that you have all of these design elements. The mock-up is mandatory if you shop. For images png, try to vectorize on illustrator to reduce the file size. Yes not, to retrieve these images, go to Illustrator > File > Assemblage
IF you have all of these, you can fill this form, then continue.
You must be logged in to your partner account to send your design made by yourself. Note that only partners can order their personalized clothing from ONE X WEAR. If you are not yet a partner, you can become it by going to the page "To become partner" in the menu "Start here".