Once you have created content and are satisfied with the results, you can directly publish the content by clicking Save and Insert. If you do not want to publish it right away, but want to do so at a later moment, click Save. The content will just be saved, so you can continue to work on it at a later moment.
It is also possible to publish the created content in the main menu of My Content. Click Insert for the content concerned to publish it in Brightspace.