Q. How do I use the nets to keep bugs away from my cabbage leaves?
You probably have little green caterpillars (worms?) that are the larvae of the cabbage butterfly--small white with black dots on wings. I had very good organic control by picking them, and lightly dusting the plant with bath powder from the dollar store as it is inexpensive. The powder seems to dessicate the caterpillar. Of course after rain it will need to be reapplied. Also a butterfly net can be taken into the garden and the butterflies caught and squashed! An organic approach is recommended as the pesticide powders get into the leaves and are hard to get off before being eaten by people.