Answer: Okay so. As the earth revolves around the sun, it stays tilting in the same way (yes it moves a little but not drastically for you to worry about) As it moves around the sun, the parts that were closer to the sun/were more exposed are shifting as the earth revolves around. This causes the areas that were currently in the summer months to cool down into the fall and winter months. That also means that the areas that were experiencing winter are now going into the spring and summer months.
Example: as China goes into the fall and winter months, America is going into spring and summer.