Hello Kitty, Ms. Grammar here.
It's much better than your original post. First, let's tackle that spelling:
Believe is spelled believe (there's a lie in there - how's that for irony?). Grammar is 'AR' at the end, not 'ER' (a very common mistake, don't feel too bad about it). Some people think that adding extra vowels to a word conveys extreme emotions better, e.g., I'm sooooo tired. It's acceptable in casual conversations, I suppose, but never in formal writing.
Believe it or not, my spelling isn't the greatest either. What's the secret of my success? My best friend is a spell checker. Most word processing programs come with a built-in spell checker, so use it. If you are entering text into a text area field on a web page, you can copy and paste it into a word processing program to check the spelling before you post. Alternately, there are some online spell checkers (like SpellCheck.net) that will allow you to do the same thing. Or just download a browser, like Firefox, that has a built-in spell checker.
Now let's tackle that grammar:
The personal pronoun "I" is always capitalized, as are all proper nouns (the name of a person, place or thing: i.e., Nanaea, Ireland, Hacky Sack). Using a lowercase 'i' when referring to oneself online is, unfortunately, common practice borne of laziness. How hard is it to hit the 'shift' key, really? Not only is it grammatically incorrect, but it also speaks volumes about how self-confident a person feels. If you can't respect yourself enough to capitalize 'I', then how can you expect anyone else to respect you? (I apologize if that sounds a bit harsh, but it's a pet peeve of mine.)
Here's how your post should have been written:
I'm gonna break it apart for you and explain my choices sentence by sentence.
Here's your first lesson: A sentence is a group of words that expresses a complete thought. Repeat it to yourself three times, out loud. A sentence always begins with a capital letter, and ends with a punctuation mark (most often, it's a period).
"Thank you," is a complete thought. You can say it by itself, and people will understand what you mean.
"Believe it or not, I do read books," is the next complete thought. You need a comma in there, after not, because I do read books is an independent clause - it has everything it needs to make sense, but the portion before it is a dependent clause, it needs the portion after the comma to make sense.
"Grammar and spelling just come very hard for me," is your next complete thought.
"Thank you so much, and I hope that none of my fics turn out to be insulting," is a compound sentence. It is essentially two complete sentences joined together by a conjunction (and). A comma always comes before the conjunction (and, but, or, nor, yet, so...) in a compound sentence. Also, insulting probably wasn't the best word to express your concern here. Offensive would have been a better choice. If you don't understand why, then look both words up in a dictionary (like Merriam-Webster Online).
Your next complete thought is, "If they are, please tell me before I make a total fool of myself." There is a comma after are because the portion before it is (I believe) an adverbial phrase (it modifies what comes after the comma). Alright, this one I'm not 100% sure on. I'm not a professional grammarian after all. Sheesh!
"Well, I'm off to practice my grammar and read more books," is your next complete thought. There is a comma after well because it is an interjection - it's shoved in front of the sentence, but isn't really necessary to the meaning. It does, however (there's another interjection!), affect the tone, so it's not completely useless.
"Thank you all so much!" is your last complete thought. I added an exclamation point to show heartfelt emotion. Oh, and you're welcome.
Last, but certainly not least, is your post script; "P.S. Was my spelling and/or grammar better this time around?" And/or gets a nifty virgule, better known as a slash around here. The virgule represents alternatives that exist simultaneously, or are offered up as possible choices.
Please note that my example is just one of several possible interpretations. The rules of grammar do have a certain amount of flexibility inherent in them.
I would also suggest a trip to the library to check out some basic grammar, usage and mechanics books. Karen Elizabeth Gordon has some wonderful books that aren't the slightest bit boring, but you might want to start with something simpler first.