How to take pictures by activating zoom with Nikon d5100?

I want to take photos by zooming the subject with my d5100

You take the zoom ring in your hand and you twist it until you're satisfied. Then you press the button. Simple.

Well go on then - use zoom ring & press button - how difficult can it be?

Look in viewfinder. Frame your shot, push the shutter button.

There are four parts to activating the zoom.

Your thumb and forefinger(s) as you rotate the zoom ring on the lens.
Your eye as you see the differences caused by your zooming.
Your brain as you decide which composition and framing is best.