Question on Agarose Plate Assay Protocol - (Apr/09/2015 )

For my class I have to summarize few papers (like journal club) and I have one question about the method.

From the paper, "A Synthetic Genetic Edge Detection Program" (http://www.sciencedirect.com/science/article/pii/S0092867409005091), there is a detailed protocol "Quick Edge Detection Protocol" in supplemental data. In step 11, is it saying pour inoculated agarose solution with cells into EMPTY Petri Dish? Or is it assuming you have already prepared solid layer of inoculated agarose solution without cells in Petri Dish that you pour solution with cells on top of the solid layer?

I am new to microbiology so I don't know if preparing agar plate is so basic that they omit such step or not.

Thanks

Tabor, Jeffrey J., et al. "A synthetic genetic edge detection program." Cell 137.7 (2009): 1272-1281.

it is as you read it: you just add the agar (liquid) to an empty plate. The agar contains the cells , so after solidifying you will have cells embedded in your agar.

They actually explain it in the first 6-7 steps...

You add (in the end) the 15ml of agarose (+ the 150µl bacterial culture) to an empty petri dish.

15ml is the volume you add to an empty petri dish (lets say between 15ml and 25 ml)