This query could be interpreted in a few different ways depending on what you are looking for. Are you interested in: Official Roland software and legacy support? Third-party style/tone libraries and user-created patches? Instructional content on how to load sounds into the keyboard?
Once you create a tone you love (e.g., a "Blade Runner Brass" or "Ambient Bells"), save it to disk. You have now created a custom worthy of sharing with the community. roland e500 tones download