A Container

HEADER
LEFT
MIDDLE
RIGHT

A Container inside another Container

HEADER
LEFT
HEADER
LEFT
MIDDLE
RIGHT
RIGHT

A Container inside another Container:

Removing the left and right bars from the inner Container and adjusting the middle width

HEADER
LEFT
HEADER
LEFT
MIDDLE
RIGHT
RIGHT

A Container with two columns made by Containers

HEADER
LEFT
HEADER
LEFT
MIDDLE
RIGHT
HEADER
LEFT
MIDDLE
RIGHT
RIGHT

A Container with two rows, each one having two columns, made by Containers

HEADER
LEFT
HEADER
LEFT
HEADER
LEFT
MIDDLE
RIGHT
HEADER
LEFT
MIDDLE
RIGHT
RIGHT
HEADER
LEFT
HEADER
LEFT
MIDDLE
RIGHT
HEADER
LEFT
MIDDLE
RIGHT
RIGHT
RIGHT

A Container containing a grid with two rows, each one having two columns, made by Containers

HEADER
LEFT
HEADER
LEFT
HEADER
LEFT
MIDDLE
RIGHT
HEADER
LEFT
MIDDLE
RIGHT
RIGHT
HEADER
LEFT
HEADER
LEFT
MIDDLE
RIGHT
HEADER
LEFT
MIDDLE
RIGHT
RIGHT
RIGHT

Using these examples as base, it is possible to create any layout desired.