Answer :
Divide your weight in kilograms by your height in meters then divide the answer by your height again to get your Body mass :)
This answer is not really going to describe how to measure your mass.
That would be a difficult thing to do, and you really don't have the equipment
to do it with.
But this will tell you how to find out what your mass is:
-- Weigh yourself. A bathroom scale is the most convenient way to do it.
-- Assuming that ...
> you're weighing yourself on the Earth's surface or near it;
> the scale tells you your weight in pounds;
Take your weight in pounds.
Divide it by 2.205
OR
Multiply it by 0.4536 .
-- The answer is your mass, in kilograms.
===========================================
If you're using a Metric scale, then the dial will say "kilograms" on it,
and it'll say that the number on the dial is your "weight" in kilograms.
This is unfortunate, misleading, and a totally wrong way to look at it.
But if you're using the scale on Earth, then the number on the dial is
your mass, in kilograms.