All you have to do is copy and paste the chapters into a word document. I've found that 36 point font looks the best for the header and 12 point font looks the best for the actual writing.

Make sure that you have all new chapters on a new page for it to look right. 

Then, save your fic. If you're using a MAC make sure to save it as a word document and not as .pages

Now you're ready to take convert to PFD format. Go to this website and upload your document. (You don't have to fill anything out)

Then convert the file.

After that's done you most likely want to add a cover and make it generally look better.

Download this program.

Next, locate your file.

And add your file.

It should show up like this:

And you want to edit that.

Edit all this to your liking: (i usually make a cover in photoshop)

Lastly, click OK and plug your e-reader in, then simply send it to your device