In Lime Event, you can can use background images.
Take a block from the Design block area to choose your background. You can choose a solid color or an image. You can also decide how the background image will be displayed.
NOTE: Background images aren’t like regular images, which are always displayed in their entirety. Rather, backgrounds image may be cropped depending on where your emails are read. For that reason, don’t use important images with logos or text as background images, as it’s not guaranteed that everything will be displayed.
If you want a complete image that’s always visible in its entirety, use a standard image block. If you want to make this image as big as possible, change the Design block area settings. Increase the maximum width to 3000 and set the padding left and right to 0.