Welcome, I'm also new to the eBookwise and am really loving the experience. You can
convert other ebook formats, but it's not entirely simple. That is, there's nothing you can just click to make it happen. This means you will have to experiment with some of the solutions described in various places on mobileread (links to follow). The advantage is that once you learn a solution, it will
be easy to work with files because you will have been forced to learn the process inside out. Not that that eases the pain of the learning curve.
I've not actually tried any of the format conversion tools myself yet, aside from the eBookwise website's free tool for .html and Word documents. The instructions for this process are here: <http://www.ebookwise.com/servlet/mw?....htm&si=43#ETI
Now, if you want to buy newer books that aren't available at fictionwise, it sounds like the easiest and nicest conversion is from the Microsoft Reader format (.lit), which is available at several ebooks stores such as Books on Board: <http://www.booksonboard.com/index.html?ebooks=ebooks
>. Again, the process is not as easy as just click and go, but nrapallo has made a program and written up detailed instructions on how to remove the DRM (copy protection) and convert .lit files to .imp in one fell swoop, which you can read about and download here: <https://www.mobileread.com/forums/showthread.php?t=20592
>. As I said before, I have not tried this, but it seems like the simplest conversion from a commercial format, and people have said that it gives really nice results, so this would be my first choice. There are quite a few steps involved, but if you take a deep breath and work through them one by one, it seems like it should be fairly straightforward. lol, if you are not so technologically inclined, you could always ask your kids or spouse for help with stuff like creating empty files. (BTW, all this assumes you are using a Windows; if you're on a Mac, I'm not sure what tools are available).
Now, as far as getting the converted books onto your eBookwise--if you can figure it out, impserve is really slick. See: <https://www.mobileread.com/forums/showthread.php?t=28363
Otherwise, if that looks too daunting you can use the $15 eBookwise Librarian (aka GEB Librarian) by simply dragging the converted books into a folder (see second link below). For buying/install eBookwise Librarian, check out <http://www.ebookwise.com/servlet/mw?...bi=28181&si=43
>. For the brief, easy instructions on using the eBookwise Librarian to transfer your converted .imp files, check out: <https://www.mobileread.com/forums/showthread.php?t=21069
>. Just remember that the GEB Librarian they're referring to is only an older version of eBookwise Librarian, so the process should be just the same.
Hope this helps. Really, the only step-by-step instructions possible are those included with the links above.