Once you have a Premium Creator account, you will be given access to your own personal Marketplace shop. You can then submit Courses to the Marketplace for purchase.
So, if you’re account is a Basic account (free version), the first thing you need to do is to upgrade your account to Premium – see here.
Then you have the access you need. The next steps are to create your Courses and your seller profile. Once this is done, submit your Courses to the Marketplace and create an overview page.
The more detail and relevance on your overview page, the more likely it will be that your Course will appear in front of the right audience.