uploading free ebook

Hi,
I am trying to upload a free ebook to my site.
I have saved the ebook to PDF and have a cover for the book.
I have saved both the ebook and book cover to my media file.
I have created a post and uploaded both the ebook cover and text saying free ebook, both with a link to the ebook.
When in preview I click on the ‘free ebook link’ it comes up fine.
When I click on the ebook image cover I end up looking at a lot of jumbled text.
I tried changing the image to something else to see if that worked but the same thing happened
Not sure what I am doing wrong, have been following youtube videos and doing everything they say, can’t for the life of me figure it out.
Any help would be appreciated.
Thanks ??