Turning - You can steer the skateboard side to side by leaning. It depends on how tight or loose you set you trucks. Keep the board tight as a beginner. As you progress loosen it up to a place you feel most comfortable. I ride loose trucks. It lets me turn quickly. This is only after years of developing muscle, balance and control. Many experienced skaters use tight trucks. It is a preference. You will find how you like it as you get better at skateboarding.
When you lean to one side the skateboard will turn to that side. The skateboard will deck will tip to the side you are turning. This tipping squishes the bushings in the trucks on one side. Causing them to pivot around the kingpin bolt on the bottom. The pivoting turns the hanger and wheels to an angle.
When both trucks turn to one side the wheels get closer together. They get farther apart on the far side. This steers the board in the direction of the lean. It allows you to turn.
The angle it tips to will help you stay on the board through the turn.
When rolling in proper stance shift your weight from the ball of your feet to your heels. This will tip the deck and cause the skateboard to turn to the side.
When you lean to the toe side the board will turn that direction. When you lean to the heel side it will turn that way.
You can adjust how much the skateboard will turn by tightening or loosening the nut on the kingpin. The 9/16" nut can be adjusted to make the board stiff. This will keep it from turning.
You can loosen the nut and this will make the board turn with less effort. Feeling wobbly and loose to the beginner.
As a beginner it will be much easier to learn to skateboard with tighter trucks. You will be more stable while you get used to the feel of the board. As you get better you can loosen them up a bit to allow better turning and more control.
Start rolling and practice turning by leaning. The faster you go the more you will notice the turning. Doing this will help you understand how the board works. Getting that board feel will prepare you more maneuvers like the tic-tac and kickturn.