video is worth a thousand words, but let me explain as best I can with words.
Take your left hand and grip the base of your erect shaft, grip very low on the base. Then take your right hand in a reverse grip, thumb pointing down but gripped firmly around the shaft, firmly squeeze (with lube) mainly squeezing with your thumb and your index finger, slowly up the shaft, focusing your pressure on the sides of the shaft. Halfway up pause and hold while kegeling. Then continue up the shaft as if you are trying to squeeze very thick toothpaste out of a tube.
That is the best way I can describe it, take it easy to avoid injury. I do sets of 15.