Once you hit the publish button after creating the course, your course would be visible in your Store.
However, if you have published your course, but it is still not available in the Course Store, you might be doing the most common mistake.
Go to the Course which you want to publish in the Course Store & click on Details.
Now select "Pricing" & check "List course for sale". If it's marked "none", it has not been published. To change it, tick the boxes on "Website" or "Android" or "iOS" as per your requirement. Finally "submit" to save the changes.
Now, go back to your Course Store, the course will be published.