I want to know the difference between these expressions "for myself" and "by myself", because I don't know how I should use them, for example:
I had studied English for myself until I attended a school.
I had studied English by myself until I attended a school.
At the previous sentences which one is correct?, or are both correct? If they're both correct, what is the exactly difference between "for myself" and "by myself"?, in any sentence.