Ereader windows 8

I want to download and read some ebooks from makeuseof.com
The epub downloads, but it opens in gibberish so i went to windows store and installed Bookviser.
Now how do i get the epub download out of the download file and into bookviser to read the frigging thing!
I know i can read them with the PDF, but that is on-line only. It doesn't download.

I just downloaded a PDF from them - click on download and it opens in a new tab (on internet explorer). Then click save as and it will save a PDF. That worked fine - it is not on line only if you save the tab that opens.

For e-book format (ebub etc formats) I use calibre - E-book management (I use a separate Kindle ereader) so I don't know about bookviser. With Calibre you have to open the program and import the book you have downloaded - I'm sure you'll have to do the same thing.