BigJohn ... first to the sock ... it should probably be an ankle length style sock, half or three-quarter filled with rice and sewn up or secured at the top. And the type of rice doesn't matter ... you can even use other grains ... wheat, barley etc. But rice is probably easiest.
Microwave ovens will vary, but I usually zap mine on full power for 40 seconds. Two minutes sounds way too much unless your oven is hamster-powered
And then I wrap the sock around Mr Happy and occasionally I use a shoe lace to keep it in place ... but your jocks might be sufficient to hold it.
Then I shave and brush my teeth while my 10 minutes of warm up is happening.
So you don't stick your schlong
in the rice sock ... you wrap the heated sock
around your schlong.
Make sense?
Cheers