You can't, sorry. With normal cold composting, if you put seedy weeds into the compost bin then you will get weeds growing afterwards. I stopped surface dressing of my garden compost many years ago and now use it in the vegetable garden where I dig a trench, put the compost in the bottom of it cover it over with soil and plant the veggies on top.

The only viable way you could do this is to cook them by allowing the compost to create a thermal reaction which will sterilise any seeds and weeds. This happens when the vegetable matter breaks down and the natural biological process causes a lot of heat.

And the ordinary garden compost heap, although warm inside, just doesn't generate the heat required to kill off weed seeds.