Launch the App
Locate the Book (You can use the search button at the top-right)
Click on the Book
Click on BUY
You will be redirect to the refill page if you don't have enough money
After Refilling or If you have enough money in your wallet, click on BUY
Then Click on download to download and read the book (Note: It shows DOWNLOADING when the book is being downloaded)
You can also ADD to LIBRARY on the download page
After Download, you will see an option that says
START READING