Put the sand into a trash bag, and roll it into the shape of a
ball.
Wraps it further into 3-4 trash bags. (This is to protect the
bag from splitting).
Roll the bag of sand to the bottom of the heavybag.
OPTIONAL STEP, Goto your local carpet store and buy a piece of
foam the width/height of the bag. Line the bag with foam. Lining
the bag keeps it from looking lumpy.
Fill the bag with old clothes, normally you can buy old clothes
from salvation army or look under rags in your local yellow pages.
Pack the bags down into the bag with a 2 by 4.
Note: Over time the filling will settle in, at that point you
will need to add more filling.
Buy a 30 or 40lb bag of sand.