Download and install the iTunes program on your computer.
Double-click the "iTunes" icon on your PC desktop, or click the iTunes icon located on the Dock of your Macintosh computer's screen to run the program.
Click "iTunes" at the top of the screen on your Macintosh computer, and select "Preferences" from the pull-down menu. For PCs, click "Edit" at the top of the iTunes menu and select "Preferences."
Choose the "Import Settings" button, and select the pull-down menu next to "Import Using." Click "MP3 Encoder" from the menu and click the pull-down menu next to "Setting" and select the audio quality you wish to use. To maintain audio quality, select "High Quality (192 kbps)." Click "OK" to save the new settings.
Click "OK" in the General window to return to the iTunes' main menu, and drag the audiobook file to the iTunes' sidebar. Alternatively, click "File" at the top of the program window, select "Add to Library" and double-click the audiobook to add it to iTunes.
Click "Books" in the iTunes' sidebar to locate the audiobook, or type the name of the audiobook in the "Search" bar in the upper-right corner of the iTunes window.
Right-click the audiobook, and click "Create MP3 Version" on the pop-up menu.