First notebook entry: Introducing myself

I study English because its internation language and almost people study English around the world

In American English, I would say:

First part:  I'm studying English because it's an international laguage ...

  or:          I study English because it's an international language...

For the second part there are also two possibilities, one emphasizing ''people" and the other emphasizing ''language."

..and most people in the world study English.

...and the language most studied around the world is English.