Hi Mate, this tutorial should help you: - YouTube
Instead of using the Punch animation you obviously want to use the Strafing Left and right animation, then I guess just follow the rest of the tutorial, you may find that if you press the button and your not moving the animation may still play but you wont be moving, if that does happen you will probably need to make a Strafing idle animation and make an animation which kind of states when in Strafing left or right but not moving play idle animation this is just a quick sketch, but there the fundamentals.
Hope that helps.