I'm new in Australia but in 2016 I'm going to join high school. How do I settle there can get some tips?

Focus on the school work and make grades a PRIORITY.

Try to join sports or clubs that interest you. Make sure your grades don't suffer by taking on too many outside activities. So, do enough to make friends, but not too much to cause added stress.

But they think that I'm unknowing

But they think that I'm unknowing
Who thinks that and unknowing about what?

Where is the problems? Normal school work, math, science, and the such are the same,
Issues in areas of history (you may not know the national history well)

Is English your main language ? If not, there can be an issue there? I am sending several students from China to Australia this year and we gave them about 6 months of extra tutoring in history and culture, along with English and bought their math and science up to normal levels.

I am good at everything you have typed in the first paragraph. I'm even good at more fields than that.

And they hate me because they think that I'm not an pure aussie.