The content library is for pre-installed (or downloadable) galleries only. Whatever the widget manufacturer makes available for that feature is what is available.
If you want to create your own slide show, you can make one and play it on Media Play.
I've tried to download pictures that are my own to my LED TV unsuccessfully. I created a directory 'Galery' in a FAT-16 USB pen drive and downloaded jpg images to 2 sub-directories under it.
Media Play will play the slide shows w/o a problem. Content Library will list the USB drive but will not download anything to the TV. The TV User's Guide is scant about all this.
Any pointers appreciated. My 'Galery' directory was not the only one in the USB drive, so I don't know if that's the problem. Would the subdirectories under it be a problem as well?