I learned it from my mother.

Like Elliot said, if its a English speaking country, they learn from their moms (or parents in general). In other countries, sometimes they learn from school. You can also attend courses for language proficiency outside the school if you want to. Then there is TV and the internet. Hard to stay away from English really ;)

I grew up watching English cartoons, movies and TV shows. Of course, I was taught English at school. However, the fact is, by the time I joined it I could converse well enough in English. I still believe watching good movies and TV shows in the language you want to learn is an excellent way to improve your speaking skills. Likewise, reading good books in the language you are interested in learning can improve your reading and writing skills.

i learn it from songs, movies and TV shows at first and four years ago , i studied it at the university and now i'm improving it by writing ^_^

I learned it mostly from songs, and later I decided to study only on English textbooks (some were actually by Chinese writers) while at the University. English teaching in Italy was very poor when I was attending school.