Vertex editing basically helps you to move the edge of the brush in virtually any direction that you please. I'll show you how to move the vertex of a simple brush.
Basic vertex editing here refers to moving a single vertex one at a time.
The aim is to move a few vertices of the first room onto the second room. Make the two rooms 512x512x512 in dimension. Ensure Vertex Snap is turned on. In this example we are concerned with only 4 of them. First select the brush so that it is highlighted in all the views.