The seasons are caused by the earths tilt, not by the distance to the sun. As the earth travels around the sun, it wobbles on its axis.
As the northern hemisphere tilts toward the sun, the days get longer. As you move north the days become longer and longer the farther north you go. Closer to the equator the difference in negligible. Near the poles the sun sometimes never sets. You've heard about Alaska being the land of the midnight sun? This is why.
The seasons in the southern hemisphere are reversed, with June, July and August being the winter months. Talk to someone in Australia to confirm this.
The days are colder in winter because the suns rays hit the earth in a more spread out manner, and the rays are more concentrated in the summer.
Think of the angle of rays hitting the planet, in winter the rays strike the earth in a more oblique angle and diffuse the heat.
The distance has nothing to do with the temp. As a matter of fact, the earth is closer to the sun in the winter.