Click "Buy Now" and the book is purchased successfully after payment. The specific operation is as follows:

1. Open the reading app, and the default interface is the bookshelf, as shown in the figure:

2. Choose the books you want to buy under the three categories of "publications", "boys' novels" and "girls' novels";

3. Click on the book and find "Buy Now" in the lower left corner of the page, as shown in the figure below:

4. After clicking "Buy Now", the following payment menu will pop up. Select the appropriate payment method and complete the purchase: