How do you ur scalp is tingling???

i mage my scalp to make it grow out more but i know that u have to feel that tingle or feel the blood pumping through ur scalp in order for it to make ur hair follicles grow. but how do you know its tingling?? how do you know that the blood is flowing through ur scalp??? and how exactly do you use ur fingers to mage it????plz hlp!!!