Messages are separated by Projects, most of the time it is unlikely that you will have more than one project open at a time, however when you do you can simply select the Tab for the project that requires your attention
To add a new message, select the 'Add Message' button from the Action Bar, located top right hand corner
This will then open a popup window for you to enter your message, and upload any files to go with your message. Any files that you add to the message will begin automatically uploading however you will need to ensure they have fully uploaded before you click save. All files saved as long as they have uploaded, even if you cancel the message in the top right hand corner. Messages can be give an expiry date, which will soft delete the message once the provided date has passed; all soft deleted message will be hard deleted after 5 days. Click save to save and return to your Messages section