If you open the page, you will see a small button with "log in", log in to continue.
Go to campaigns now.
Scroll down and click of the bottom "start Campaign" or "create product".
You can now design products and create designs that you can then sell, just follow the instructions.
And if you have questions, feel free to contact me.
I apologize for the pictures, the language there is German, I speak German but also fluently English.