몇 학년인지요?

I got a little better a month after I started riding in-line skates.

Then I got much better over the past few months.

Now I am good enough to be able to ride even on one foot.

이렇게 쓰는 것이 의미 전달은 정확한데 나이가 어리면 힘드니

I could ride inline skates a little better one month later.

A few months later I got much better.

A few more months later, I could ride even on one foot.

정도면 되겠습니다.