[Smileydude]

topic- the doer of the action or the thing that is
object- the receiver of the action

"wa" in this case is へ　（the "he" is used for the subject particle wa) is place after the subject. It really doesn't have an english equivalent, but many people like translate it as "as for..."

let's take the sentence kore wa nan desu ka? これわなんですか (what is this?)

kore means this

"this" is the thing that is, making it the subject (this is what?, more literally)

Since "kore", this, is the subject, "wa" is placed after it to denote that. A good way to remember this is:

As for this, what is it?

and again most basically this sentence would be: This (wa) is what?

nani desu ka? makes sense because the people to whom you are speaking know what you are talking about. they understand that "this" is what you're talking about. That's the same reason why we here "genki desu ka?" (how are you/are you spirits well?) instead of "anata wa genki desu ka?" the anata wa denotes "you" as the subject (as for you, are your spirits well). this is again, not necessary because when this phrase, when asked is immediately understood as "you" as the subject, (unless otherwise stated) because, well who else would you be asking about when you are talking directly to a person?

I hope this makes sense. Try looking at lessons 1-4 on japanese-online.com. That should help even more to clear things up.