Sorry, sabrintos, there is something not clear: if you are not familiar with the multiboot process and the installing of images by OpenMultiboot, why did you post that "guide". I thought you knew about the process. Anyway, just to say, because it's clear, now, that the GUIDE repeatedly posted in this thread is the ONLY valid
Enjoy the multiboot: it's really comfortable to have the chance of testing many image without having to reflash your box. It's also useful to keep different versions of the same image in case one more recent introduced a bug