How to load PDF document into iBook?

For the PDF files - tap and hold down on the PDF - the icon or the open file - and a window will pop up that says "open in" - tap that and then select iBooks from the resulting menu.

I am not aware that you can open PowerPoint files in iBooks.

I do not know iBook. You mean iBooks on your IPad or iPhone? And the pdf's are on your iMac?

If all the answers are "yes":

Open iTunes on your iMac, on the left open the "Books" Library (if it is not there check it in iTunes/preferences and it will show), then click iTunes/File/Add To Library, a Finder window pops open and add all pdf's that you want in this popup Finder window, click "choose" in that window, and then they are in iTunes Library. Sync the iDevice with iTunes (with the correct settings for the pdf's you want to sync: all or selected).

I agree with Demo, I don't think that Powerpoint files will be opened in iPad/iBooks.

Good post. I wasn't thinking that way at all - I was ssuming that the OP was looking for a way to save a PDF on the iPad to iBooks.

I didn't know either, but could hardly copy your post 😀