The instructions for the second stage are:

Let there be an expanse between the waters to separate water from water.

Genesis 1 v 6

We can see what this means when we read:

God called the expanse 'sky'.

Genesis 1 v 8

The water round the earth is separated to form clouds and sea. There is now a space for life, but with an abundant supply of water, which is vital to sustain life.

At the third stage the instructions are:

Let the water under the sky be gathered to one place, and let dry ground appear.

Genesis 1 v 9

Let the land produce vegetation: seed-bearing plants and trees on the land that bear fruit with seed in it, according to their various kinds.

Genesis 1 v 11

Land appears together with plant life. Vegetation flourishes in the environment provided at this stage.

The fourth stage instructions are:

Let there be lights in the expanse of the sky to separate the day from the night, and let them serve as signs to mark seasons and days and years.

Genesis 1 v 14

Probably the clouds separate and the sun and moon appear. The cycle of the seasons is now established so that life can be supported.

For the fifth stage, the instruction is:

Let the water teem with living creatures, and let birds fly above the earth across the expanse of the sky.

Genesis 1 v 20

Life appears in the sea and in the air.