There is no right age to learn any of this stuff, so it's difficult to give you clear instructions. Your first job is to learn to read well, because once you're a good reader, everything else will be much easier.

What are you supposed to be learning here?

Spelling. (Some advice, and then some spelling tips.)

Punctuation. (The rules.)

Grammar. (A few important rules.)

Terminology. (A few fancy words to learn: you will sound clever if you use them.)

Reading. (A list of books which you might enjoy reading.)

Functional Writing. (Learn how to write clear text which can be understood easily.)

Creative Writing. (Learn how to write stories well.)

Poetry. (Optional, but more interesting than you might imagine.)

Literature. (Should be optional, but if you want a good pass in an English exam it may be necessary to study some works of literature and to comment on them.)