Question Regarding Mediums

I thought i understood, and i guess no matter how much i read i still do not get it. My ebb and flow came with a bud blanket, at the bottom of the tray. And rock wool cubes. These cubes are small, can they take the weight of a plant? and where would the roots go? Whats the next step, that seems like it would just be for seedling. Do i fill some pots with Grow rocks or something? Maybe the roots are not as big as i thought?

use expanded clay pellets or also called hydroton and the best stuff is made in Germany.I use ebb n grow also but mine are all in separate buckets. is yours in a flood tray

why yes it is!, its in a flood tray, and the picture on the the manual (not a very good one at that) has these cubes in alternating rows like a checkers board. And do i start the seeds off in there? do i germinate them and shove them into the rock wool and flood it with the rockwool directly on the bud blanket?. I also just realized there is no top to the tray, i thought the roots are not supposed to see the light. I am guessing you would have pots with holes on the bottom and filled up with hydroton then flood up to the holes?

ok so i found a few pages with the necessary pictures. It seems people are just putting the rockwool directly into the hydroton which fills the entire pan. Should i go about this method?