The SunTracker is a program that lets you see where the Sun is in the sky at any time of day, anywhere in the world. Just click on a date, choose a place and click on the pink button. If you want to see the movement slower just change the speed.
For example, you might want to see what the North Pole in January looks like (very dark). Or you could see Liverpool, Britain and Sydney, Australia on the same day to compare how much sunlight we all receive.
The SunTracker doesn't show you what the weather is like in a place (even though the Sun does affect the temperature). Instead it shows you how long the Sun shines on a place each day and how high the Sun appears in the sky.
To understand why these things are important to the seasons you should read the 'What causes the seasons' section.