Does the earth go further away from the sun in the winter?
The Earth is at perihelion, the closest point to the Sun at 147,000,000 km, around 3rd January. It is at aphelion, the furthest from the Sun at 152,000,000 km, in early July.
The Earth's orbit is almost circular, so the effect of distance is quite small.
It is the Earth's axial tilt, or obliquity at 23.44 degrees, which causes the seasons. At the Solstices in June and December, one hemisphere gets less than half of the incoming sunlight and is in Winter, the other hemisphere gets more than half of the incoming sunlight and is in Summer.