Help! How do I use UI button to work as an input button/axis?

I am trying to use the UI buttons to create a button on a canvas that when clicked, will work as if you pressed the button on the input axis. In this case I am trying to use the "horizontal" axis being triggered as positive or negative if you press the left or right button that display on the screen with the canvas. Please explain how to accomplish that, and if more details are needed just ask.

Thanks