Approach your horse and the "mount horse" action icon will appear.
Press the Action button to mount your horse. Controls while on horseback are listed below.

Mount horse icon
Hold the button to aim your weapon.
Hold to open the Call Menu, or tap to make a quick radio call.
Select movement direction.
Open the Pause Menu/show tips/iDroid help.
Use the iDroid data device
* Can also be used by pressing the OPTIONS button.
* The game does not pause while you use the iDroid.
Use the weapon you are aiming.
Hold down to use binoculars. Tap to reset camera perspective. While aiming a weapon, this switches between shoulder view and first-person view.
When hiding on horseback, this switches sides. Hold down to zoom the camera.
Hold the button to aim your weapon.
Hold to open the Call Menu, or tap to make a quick radio call.
Select movement direction.
Open the Pause Menu/show tips/iDroid help.
Use the iDroid data device
* Can also be used by pressing the OPTIONS button.
* The game does not pause while you use the iDroid.
Use the weapon you are aiming.
Hold down to use binoculars. Tap to reset camera perspective. While aiming a weapon, this switches between shoulder view and first-person view.
When hiding on horseback, this switches sides. Hold down to zoom the camera.