The first chapters of Genesis leave us in no doubt whatsoever about how God created the universe. On the six successive days of creation, God spoke and what He said happened. That is to say, the means that God used to create the universe and all things in it was His Word.
The occasions of his speaking, from Genesis chapter 1:3–26 (NIV), are as follows:
Day 1. And God said, ‘Let there be light’ (verse 3).
Day 2. And God said, ‘Let there be an expanse between the waters to separate water from water’ (verse 6).
Day 3. And God said, ‘Let the water under the sky be gathered to one place, and let dry ground appear’ (verse 9). Then God said, ‘Let the land produce vegetation: seedbearing plants and trees on the land that bear fruit with seed in it, according to their various kinds’ (verse 11).
Day 4. And God said, ‘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, and let them be lights in the expanse of the sky to give light on the earth’ (verses 14–15).
Day 5. And God said, ‘Let the water teem with living creatures, and let birds fly above the earth across the expanse of the sky’ (verse 20).
Day 6. And God said, ‘Let the land produce living creatures according to their kinds: livestock, creatures that move along the ground, wild animals, each according to its kind’ (verse 24). Then God said, ‘Let us make man in our image, in our likeness, and let them rule over the creatures that move along the ground’ (verse 26).