Earth is always spinning, a little bit like a top. As it follows its once-a-year orbit around the Sun, the planet stays tilted at the same angle. As a result, Earth's northern half, including North America, is tilted away from the Sun during part of the year and toward the Sun for the rest of the year.
From September to March, the northern half is tilted away from the Sun. During those months, this half does not get much light and heat from the Sun, which causes autumn and then winter. At the same time, the southern half is tilted toward the Sun. It receives more light and heat, so it goes through spring and summer.
In March, the northern half of Earth begins to tilt toward the Sun. As more of the Sun's energy hits this half, it goes through spring and summer. At that time, the southern half begins to tilt away from the Sun, so it experiences autumn and winter