When you open the book, you'll have the option to "download" or "read online". Choose "read online".
Each book's description lists the number of users that can access the book at the same time. If a book is 1 or 3 user and you can't access it, come back later to try again.
If you have problems accessing the e-books you should contact Discovery Services at reachout@msu.edu or 517-353-8700.