Adding a cover to ebook does not size correctly

I have been trying to use different image conversion, pdf combiners, etc. on google to accomplish one simple task.

Replace the first page of:

Think Python - How to Think Like a Computer Scientist.pdf

With the hard cover image:

front page.pdf

It seems like there are some Edit tools in the premium version of Adobe that could do this quite easily. Every time I combine the files, the cover is either HUGE or really tiny. Since the textbook pages are "8.50x11.0" I tried to resize the cover to that size but that also did not work when combining the files.

Could someone do me the courtesy of adding the hard cover image to this PDF file? My eternal gratitude awaits you.