You can install jInbound using Joomla's built-in extensions installer.
- In your Joomla control panel, go to "Extensions" > "Manage" > "Install":
 

- You will see the "Extensions: Install" administrative page, as shown on the next image.
 - On the tab "Upload Package File", click the green button:
 

- In the "Open File" box, find the JoomlaShack extension you need to install.
 - Click on the file name twice.
 - After a few moments of screen activity, you will see one or a few successful installation messages on a light green background, similar to what you see in the next image:
 

