If you want it to be one of your content types on top, you can change the name for one of the 4 content types to "Daily Journal". Then you can decide if only admin can post it, or all members. More explanation is provided here8.
If you want to make sure that only specific members inside the community are able to see your journals, you need to post it inside a group7.
If the journal is something that you want everyone to have access to, for the sake of gathering all the journals under one page, you can create a topic and call it "Journal" and anytime you post a journal, add the topic to the post.