You can upload your own creative messages using File Uploader.
        
            You can upload 
                    - a .zip file that contains an index.html as well as any needed CSS or
                        images
- a single HTML file with all CSS and images base64 encoded and embedded
                        inline
Alternatively, you can build messages easily using the Message Builder.
         
        - 
                Enter a descriptive name for your message.
            
- 
                Select the positioning of your message. You can choose
                        Center, Top,
                        Bottom, or Full Page
                        Interstitial.
            
- 
                Click Upload File. Select your file. Click
                        Open.
            
- 
                Click View on Devices to preview your message.
            
- 
                If you are conducting a test, add any other test messages by clicking
                        Add Another Message.
            
- 
                Click Save & Continue.
            
Once you're done uploading, 
finish your campaign.