understanding grammar

As an English Major I constantly find myself correcting my own grammar. As it can be overwhelming for anyone, I feel that it is important, as future teacher to understand every bit of grammar possible. Because how can one teach to others what they are unsure of or do not know? I am not only taking this class because it is required, but because I need to know how explain parts of the English language.I feel that my biggest issue has to do with my over usage of commas. I've never had a teacher or professor tell me that I've been using, or have used them wrong. It's just that I have never really been sure if I am using them right. I guess I just put them wherever I feel they should go or feel like they fall comfortably. And, whenever I read over my blogs, essays or journal entries, I notice that there's commas every where!In addition to my addiction to commas, I really want to know how to break apart sentences and know what each part is called (antecedents, prefixes to words, etc). I remember in school learning them, but I never really learned them. I figured, I know how to write a sentence, why do I need to know what the parts are? I now regret not parking those parts into the back of my brain. I think that by knowing parts of the sentence I will be able to choose the right words and have the ability to create strong sentences. Also, using words in the right content are really important to me; such examples as, "lay down" and "lie down" or "farther" and "further." I just have a hard time knowing which ones should be used for what type of sentence. Hence, wanting to know the parts of a sentence.Overall, I just want to suck up as much as I can about grammar. I want to be able to use commas without thinking that they just may be in the wrong places even though Microsoft Word says they're not. I'm looking forward to finding out how to use grammar correctly and to see how my sentences, word choice, and papers becomes magnificent pieces of art over the semester (as I'm sure there is already a lot of errors with this blog).

Question: Whom or who? Does anyone have any suggestions on when and how to use the two?