More particle questions

[Diggity]

Ok, well maybe not a particle, but how to use them correctly to say something in particular. So far my Genki book has taught me - wa, ga, o, ni, de, to.

If I want to say: Yesterday I had a hamburger for lunch. How would I do it?

Kinou, watashi wa hirugohan ni hanbaagaa o tabemashita.
or this:
Kinou no hirugohan wa hanbaagaa o tabemashita.

The real thing that is throwing me off is fitting the word hirugohan in there. I know kinou is yesterday, hanbaagaa is the direct object, but what particle would go with hirugohan? I know that "ni" is a time marker. Please help! I want to be able to start putting together some more complex sentences. I think I have most of it down but stuff like:

I am going shopping for a car at 5pm.
Watashi wa goji ni kuruma o kaimono shimasu.
Well with kaimono (shopping) being a noun wouldn't it need a particle?

I guess clarifying these two statements would be a big help. Thanks!

[doitashimashite]

hey man, as for the lunch question, your first sentence looks correct to me. I am not absolutely sure, but fairly sure.

for your second question, you would connect shopping and car with "no" and then have that little phrase as the direct object.
like :
goji ni, watashi wa kuruma no kaimono o shimasu. <-romaji version
五時に、私は車の買い物をします。<- kanji verision
ごじに、わたしはくるまのかいものをします。<-hiragana version (but o and wa as they would appear in a sentence, as wo and ha

[Opgots]

If I want to say: Yesterday I had a hamburger for lunch. How would I do it?

Kinou, watashi wa hirugohan ni hanbaagaa o tabemashita.
or this:
Kinou no hirugohan wa hanbaagaa o tabemashita.

Either one would make sense. The first would be saying:
"Yesterday, I ate a hamburger at lunch time.
And the second:
"As for yesterdays lunch, I ate a hamburger."

The real thing that is throwing me off is fitting the word hirugohan in there. I know kinou is yesterday, hanbaagaa is the direct object, but what particle would go with hirugohan? I know that "ni" is a time marker.

Yes, sometimes it can be used for time. So you could use the first sentence you stated to represent that.

Please help! I want to be able to start putting together some more complex sentences. I think I have most of it down but stuff like:

I am going shopping for a car at 5pm.
Watashi wa goji ni kuruma o kaimono shimasu.
Well with kaimono (shopping) being a noun wouldn't it need a particle?

...Well, you could just change "Kaimono" back into its verb form, "Kau". After you do that, just use "Kau" as a regular verb.
Watashi wa goji ni kuruma o kaimasu. meaning:
I will be buying a car at 5.

Hope that helps.

[Diggity]

Thanks to both for the replies. Maybe if both sentences are correct at least it means I am starting to understand what sounds right at least (even if I don't fully understand why!)

The reason I am wanting to use kaimono is for this -
Watashi wa kaimono o shimasu, demo kaimasen.

I haven't learned how to connect phrases yet so I'm not wirryied if this is correct but the jist is
"I am shopping, but I'm not buying."

I wouldn't want to use kau in my car reference because I am shopping for a car... not neccesarily buying one at the time.