AFAIK, this forum is primarily for distributing public domain ebooks. You can of course upload your
complete book here, if you own the rights and don't expect any kind of payment for it.
However, as soon as you upload it here, anybody can download it.
If your book is a work in progress the
Writers' Corner is probably a better forum.
If your book is finished, you can plug it in the
Author Self-Promotions forum.