Step 1: Tap/click 'Create post' to start creating. The option is visible whenever you have sufficient permission to post. In Topics that are configured only to allow Moderators to post, other users will not be able to use the create post option.
Step 2: Select a topic that is relevant to the post you are about to create. Topics help keep the discussions focused and help get the posts in front of the right audience.
Step 3: Once your content has been posted, you'll see it visible in the space and topic. This post will then be added to the digest of others subscribed to the space. Users who have set alerts for that topic will also receive an email notification.