「は」と「が」：この二つの本当の意味

Before I start, I would like to apologize for using の twice as a particle in my title. It'd be nice if somebody mentioned a way to umm, compress it or just take one of those out, lol.

At any case, so today I got a Japanese textbook in a bookstore. It was slightly pricy, and not some fancy textbook like げんき, or even a textbook in a technical sense (It doesn't actually have a path of instruction); it's called Essential Japanese Grammar, by Tuttle, if you'd like to look it up. I like it because it's more of a nice reference tool for grammar.

At any case, so I took a read over it, and it says in one of the pages at the front side of the book that apparently は emphasizes the subject more than が (I can't type the original quote as that would violate the copyright of the book, and I just spent a few minutes trying to find it but I can't). So I got confused since I thought that は is a general subject marker whereas が emphasizes it.

For example, when I read Japanese text, I would read it in a way that, in the case of a dog being in a particular spot...
「犬はあそこにいる」would mean "A dog is there", whereas 「犬があそこにいる」would mean "The dog is there" or "A DOG is there", emphasizing the fact that the subject is a dog. This book seems to state the reverse.

So, I'm confused now. How does は and が actually work?

For God's sake, but an actual textbook and actually LEARN the language in a sensible way instead of using reference materials and asking us to type up lessons for you based on questions you think of based on your random flipping through them.

The question of は/が has been covered multiple times here and it would be appreciated if you would use the search function and go back and read at least some of the threads covering it before asking us to recreate them all anew just for you.

You can use の as many times as the situation calls for.

Yeah, you can find so many threads about the topic even only in this forum, just like these ones.

STILL confused about は and が; example sentences

は, が and を what's the difference between the following sentences?

Sorry, guys. I kinda forget to check if there were threads made before, as like some others, I believe. I'll take a look at those threads later, but I can't do so that effectively at the moment since I am using a tablet (I'm not very used to using these).
[MENTION=983]mike[/MENTION] I was going to give you a piece of my mind, but after I typed the above paragraph and looked over your reply again, it doesn't seem that hostile now.

But I request of you to please calm down; It may be a little inconvenient of me to not have a textbook and ask such a simple question, but I highly doubt it was EXCRUCIATING.

Again, I'm sorry to you two for me being a burden, but any inconvenience is purely accidental and not intended. But Mike, I've barely only been on this forum and already I feel less welcome than in the other forum I have been in for over 2 years with 3 bans. I may be wrong, but you seem to have some sort of mild hatred towards new learners. Or more likely, I have been marked as some n00b who will quit sometime soon and go back to being a Weaboo by you. If so, I wish to offer friendship in exchange for a bit less unreasonable hostility.

I regret that having given you my best advice and having had it rejected I am unable to be of any assistance to you.

This other forum you speak of, is your participation there also in relation to learning Japanese?

No, it's a Minecraft site, so, yeah.

I still can't find the page where I found the quote, so I'll take a look at those pages you guys gave me, and I'll search around. Thanks so far, sorry for the trouble. I'll just edit this post later on if I find anything, so that other guys can kinda refer to it instead of making a new thread.\

Also, completely random question, but it seems I cannot find the rules. Am I being lazy and severely missing some obvious things, or regulations are user-responsibility?

Thanks.