Learn x Study x Teach: Como utilizar

Hi there
This is my first post, actually I've just joined xD. I don't know how's the right way to describe that u r learning something. Some people told me that I gotta use "teach myself", "I teach english myself", some use "I study english myself". I've heard that "learn myself" is wrong.

I learn english (by?) myself. / I study english (by?) myself / I teach english (by?) myself.
I've been learning english (by?) myself for 2 years. / I've been learning english for 2 years.
I've been teaching english (by?) myself for 2 years. /
I've been studying english (by?) myself for 2 years.

I need some help