To transfer any eBook to your Kindle using Calibre, follow these steps:

1. Install Calibre: If you haven’t already, download and install Calibre on your computer. Calibre is a free and open-source eBook management software that allows you to organize, convert, and transfer eBooks to various devices, including Kindle.
2. Add the eBook to Calibre Library: Open Calibre and click on the “Add books” button (or drag and drop the eBook file) to add the eBook to your Calibre library. Calibre supports various eBook formats, including EPUB, MOBI, PDF, and more.
3. Connect Your Kindle to the Computer: Use a USB cable to connect your Kindle device to your computer. Calibre should automatically detect the connected Kindle.
4. Select the eBook and Click “Send to Device”: In the Calibre library, select the eBook you want to transfer to your Kindle. Then, click on the “Send to device” button in the top menu. A dropdown menu will appear.
5. Choose “Send to Main Memory” or “Send to SD Card”: In the dropdown menu, select either “Send to main memory” or “Send to SD card,” depending on where you want to store the eBook on your Kindle. If your Kindle has an SD card slot and you have an SD card inserted, you’ll see the “Send to SD card” option.
6. Transfer the eBook: Calibre will start transferring the eBook to your Kindle. Once the transfer is complete, you can safely disconnect your Kindle from the computer.
7. Check Your Kindle Library: On your Kindle, go to the “Library” section to find the transferred eBook. It should be available for reading on your Kindle.

Calibre provides additional options to manage and customize eBooks before transferring them to your Kindle. You can edit book metadata, convert eBook formats, and adjust settings for optimal reading experience on your Kindle. Explore the features of Calibre to make the most of your eBook management and Kindle transfer experience.

Remember that transferring eBooks to your Kindle via Calibre should be for books that you own or have obtained legally. Sharing copyrighted material without permission is illegal and violates intellectual property rights. Always respect the copyright of authors and publishers when dealing with eBook content.