Downloading an Arabic language keyboard is as simple as updating one's computer system preferences. The change can be made through the Control Panel of a PC or through the System Preferences of a Mac computer.
On a PC, click the Start menu on the main toolbar, and select the Control Panel option. From the Control Panel, select Change Keyboards or Other Input Methods. Next, click on the Change Keyboards button that appears on the window interface. Select the Add button, and scroll through the list that pops up until reaching the Arabic language setting. Click and drag the Arabic language option to the top of the list, and then select Arabic from the Default Input Language drop-down menu at the top of the window.
On a Mac, choose System Preferences from the drop-down menu of the Apple icon at the top left side of the screen. Select Keyboard under the Hardware section, click the button for Input Sources and choose the Arabic language setting to add. At the bottom right side of the window, check the box for Show Input Menu in Menu Bar. After this process, select the new Arabic keyboard from the menu bar at the top of the screen as indicated by a flag.