Particles & Sentences! タｓケテ!

ﾂ I am a little confuzzed about particles... i know what all of them mean, but....ok here let me give you an example to explain my question more...

it was rainy yesterday is : kino wa ame deshta
literally it means : yesterday (wa) rain was
the particle wa marks the topic or the focal point of the sentence. its often used when clarifying or stressing a particlar point. (i got that out of a book)
im not really sure what that means...also, why does the sentence leterally mean yesterday (wa) rain was? how do you put english words and japanese particles together to make the correct japanese sentence...? just the basic part of that...

wa doesn't mark the focal point so much; it's what comes after it that gets the focus when it's the topic marker.

Kinou wa ame deshita.
Speaking of yesterday, [it] was rain[y/ing].

The wa just shows that you're talking about yesterday; it doesn't necessarily mark "yesterday" as the subject. Also, deshita is more of a replacement for futteimashita than just meaning "was."

Of course, the wa here could also be the contrastive wa, in which case it would mean something like "(it isn't raining today and didn't rain the day before yesterday, but) yesterday it was raining." Sometimes it's hard to know which interpretation to give it, especially when there isn't any context.