My dream, from my childhood is becoming an astrophysicist. Now, I'm at grade 10 and I'm good at science and math. From now, how should I develop to become a good astrophysicist:)
The link Vanadium 50 told you to read is this one. But ya, in order to become an astrophysicist you need to go hard on both mathematics and physics. So focus on those subjects.
Normally one would obtain a physics degree, perhaps with a specialization in astrophysics or cosmology, and then obtain an MS and/or PhD in Astrophysics.
The best way to prepare is to take as much math as you can in high school. At the least, be prepared to start calculus in college. Many high school students also take the equivalent of the first couple of semesters of calculus while still in high school. If you can take some high school physics, that would be good, but not necessary. Physics in college will start from the ground up and assume no previous knowledge either way.