If you wish to edit the details of an existing product, first of all, please login into your Supliful account.
On the top click on your Avatar bubble and choose My Products:
Find the product you wish to update and click on the pencil icon next to it:
You will be taken to the product editor page where you can make all the necessary changes. All the updates will be saved automatically, and you will see a pop-up notification verifying that the changes have been made: