I think we have asked you this before but I'm not sure that we got an answer - why do you feel that you need to "learn grammar"? We understand your desire to learn how to write more comprehensible English but I'm not sure that, as a native English speaker, you really need to go to the effort of learning all the terminology and then practising particular aspects of it.
Why don't you post a few short pieces (stories) for us to look at and see what changes we would suggest? You will probably learn just as much from that.
Student or Learner