Every user of your company is able to create a new product.
From the products page, click on the Create a new product link.
The product creation form will then open.
To create a new product, you have at least to name it. All the other products information (fields, description, picture) can be edited afterwards.
To upload a picture to your new product, click on the "Change" button.
To create your product, click on the Create button in the top right corner.
You will then visualize the new product home. To see the actions that can be performed from there, see the related article.