Fill tub with 3 gallons of hot water for every pound of fabric (around 3 yards, depending on thickness).
Add half the bottle of Rit liquid dye for each pound of fabric or one box of powdered Rit dye per pound. If using powdered Rit, dissolve the powder in 2 cups of hot water prior to adding it to the tub.
Soak the item being dyed in clean warm water until thoroughly wet. Remove the item from the water, wring out excess water and smooth it out so that every bit gets dyed evenly.
Add the item to the dye tub and stir it constantly for 10 to 30 minutes, depending on how deep you want the color to be.
Drain the tub, then rinse the dyed item in warm water. Continue the rinsing with cooler water until the water runs clear.
Wash the dyed fabric in warm water and rinse it in cool water again.
Dry the piece in the dryer or allow it to air dry, according to personal preference and the clothing manufacturer's directions.