This question came from a Tribe graduate and Tribe teacher Raquel shares a simple answer.
Moola Bandha for men I guess should be explained by men but from speaking with advanced male practitioners, like Mark, the best way to teach it to beginners would be to ask them to visualise the bottom area of the pelvis divided in three parts: anus, testicles and the area between both, then exercise contracting the 3, then release the anus, then release the testicles contraction. The very subtle contraction left will be a physical application of moola bhanda.
For me personally it is an experience that comes with time and practice, as with everything in yoga, especially when it comes to muscles that we are not familiar with. At the beginning you can explain it as a gentle contraction of the perineum area which is between the testes and the anus (everyone should be able to feel these ).
Because yoga practices need time and maturation, and doesn´t only have an effect on the physical body, I personally wouldn’t make a big deal of moola bhanda for beginners as it is something that spontaneously will happen once the skeletal system has realigned and the deep muscles of the lower abdomen have been accessed and trained. Every time you practice any standing poses broadening and lengthening the feet and lifting from there upwards while surrendering your weight to the earth uddiyana bhanda will engage and that will ‘pull’ moola bhanda up (engage moola bhanda). In forward bends it is more obvious. If your maintain a long spine and allow enough space between the hips moving forwards and the thighs moving back or down moola bhanda and uddiyana bhanda will engage.