How to take good photos inside a basketball stadium?

I have a nikon d3000 an i'm a beginner photographer and i sometimes go to my brothers basketball to photograph him playing but the pictures turn out really blurry or really dark. Any tips?

Get different lenses and sit court side?

There's a reason they come out blurry. To freeze action you need a fast shutter speed. The problem is with a fast shutter you are not letting in much light. You need to either use a high ISO(increase your camera's sensitivity to light) or use a lens that will let you open up to a large aperture(letting in more light). You have a D3000 so I know you can adjust your ISO. Turn it up to 1000 or higher, and shoot in shuttter priority at at least 1/125th shutter speed. The camera will then adjust the aperture for you.