oh no, we're both talking about the same thing, don't worry
with eBook Publisher, you make an imp by first importing your source files (html, word, whathaveyou), saving and intermediary "container" file, then from that you "build" your book (you can export to imp for the 1150, imp for the 1200, and / or oeb (or is it opf ?? arg, where are nick and dale when you need them...).
it sounds complicated (and it is a *tiny* bit, at first) but the manual* gives you step by step instructions. by the way, the manual is also available here as an .imp book, so you can read along as you go, and use the search function and such. i can't remember whether it is in the ebooks section or the eb1150 section but a search should bring it up. i beleive DaleDe uploaded it, if you want to add that detail to your search to narrow the results.
nick and dalede know millions of times more about this than i do, by the way (i can tell i'm not doing a good job with my explanation
if you don't want to worry about ebook publisher for now, definitely try out mobi2imp, which you can get here (check the stickies). that's the tool nick (nrapallo) made. it's brilliant ; completely effortless. if you have any mobi format books around (.prc) definitely use that.
*by manual i mean the help file.