Plan ahead to decide where you want to store your eBook on your computer. When you download your eBook, a dialog box will open, asking you if you want to save the eBook file. Next to the Save button may be an arrow. When you select that arrow, one of the options will be Save As. Clicking the Save As link will open a window that allows you to browse through your computer folders and select the folder in which you wish to save your eBook.
If you have downloaded your eBook without choosing where to store it, you can find the folder where your computer saves downloads by doing a search or find in your computer’s file management system and typing in the name of the book.