You don't need to hold down your 'w' key when strafing. All this needs to be done while holding down your space bar so that you can gain speed and jump on the platforms throughout the map. The same goes for strafing to the right but you move your mouse to the right while holding down 'a'.
For example when you want to strafe to the left you would move your mouse to the left and hold down 'd'.
To strafe you need to use your 'a' and 'd' keys while moving your mouse. You will also need to know/learn how to strafe so that you can keep your speed during a map and so that you can land on the platforms that get you around the map. This is one of the main features of bhop as it allows you to continuously jump so that you can build up speed to complete the map in a faster time then you would if you were just walking/running. To start with you will notice that if you hold your space bar you will continuously jump.