First, calculate the mass of the hypochlorite you will need in your final solution. I doubt you will have a hypochlorite as a solid, but if - just weight it and then add enough water to make 1l (it is not the same as adding 1l!). If you have concentrated hypochlorite solution - find out what volume contains requested mass of hypochlorite. You may need density for that, unless you know what is %w/w cocentration and you can weight solution instead of measuring volume.