We've created this Forum Thread with some workarounds and advice to assist you in publishing you ebook.
Sizing of Cover images
I am a complete newcomer to Lulu. I am trying to insert an image into the cover. I have sized the image to reflect the size constraints given in the template at 300dpi but on dragging it across the image expands so that the vertical extremities exceed the space. How can I get the image to remain the size that I have set?