How can someone who is changeless do anything at all?

The Bible states that God spoke and created light on the first day of creation (Genesis 1:3). On subsequent days He created other elements of the universe, and on the seventh day He rested (Genesis 2:2).

The Bible also tells us that God does not change (Malachi 3:6; Psalm 102:27; Isaiah 46:4).

To many, this seems to be contradictory. It isn't.

The Christian God is viewed as omnitemporal, meaning that all moments are inherently inhabited by Him, and He Himself is no different from one moment to the next. The Christian God is also viewed as omnipresent, meaning that all locations are inherently inhabited by Him, and He Himself is no different from one location to the next.

So God is the same everywhere, and He is also the same everywhen.

Now consider the following situation. Imagine I am standing next to a room, such that the room is to my left. As a believer, I can here accurately say "God is present in the room to my left". If I then change my location such that the room is now to my right, and there is no longer any room to my left, I can no longer make the statement "God is present in the room to my left". The statement about God that was true from one location is not true from another location, but it would be incorrect to argue that God Himself is any different.

The location is different. God is not.

Let's compare this with omnitemporality.

Imagine Adam awakening to witness the creation of Eve on Day Six. As a believer, Adam can now accurately say "God is creating woman today". If Adam then allows the day to pass, and waits for the onset of Day Seven, it would not be accurate for him to say "God is creating woman today". The statement about God that was true from one moment is not true from another moment, but it would be incorrect to argue that God Himself is any different.

The day is different. God is not.

It appears to humans that God changes over time, but the reality is that time changes under God.
(Psalm 90:4; Ecclesiastes 3:1; Job 38:12; Acts 17:26; 1 Timothy 1:17; Hebrews 9:14; 2 Peter 3:8; Revelation 22:13)