At it's simplest, you just put the books on the device and read. But, you will probably need to sort out a font. If the book has an embedded font, you will need to select "Publisher Default" as the font when reading. If it doesn't have an embedded font, then you will need to install a font and select that when reading. The first post of
https://www.mobileread.com/forums/sho...d.php?t=204363 has instructions.
The other thing to consider is converting the books to kepubs. The reader application used for kepubs handles RTL fonts better than the epub application.