You can replace the Chintaro logo in the top right corner of the home screen with you own logo.
Save the required logo as a gif file called Logo.gif in the \Chintaro\Data folder. If there's already a file there called logo.gif, then replace it.
You can use Paint to change you logo to a Gif file. Just open the file with Paint and click File>Save As and Choose Gif file from the list.