Go to your downloads folder, locate Bookshelf.dmg, and double-click on it to open the installer.
Install Bookshelf
Drag the Bookshelf icon to the Application Folder inside the Bookshelf Installer. If prompted, enter your Mac's password to complete the installation.
Add to Dock
Go to your Application folder and Double Click Bookshelf to launch the app. Click and hold on the Bookshelf icon in your dock, then choose Option > Keep in Dock to add Bookshelf to your dock.