I think the main idea of this text is: 

To talk about facts about possums and what they hunt when they go out into the bushes.

One example of a supporting detail is:

This site tells us kids facts and it tells you facts about them.

Another example of a supporting detail is:

This site also tells us about different types of possums and also they tell you about their life span.

It is clear that the main idea is telling us kids facts about possums.

Because they want to tell us what we need to know.