For example, If i wanted to say, "A sandwich" or "A car tire" in chinese, How would i say that, and where does the "a" go? At the end of the sentence, or at the beginning like in english.

And i also want to know the translation to "a" in chinese, And how would i write the "a" because google translate isn't a very good source for east asian languages, (Or any other language really except english.)

Oh, and uh, I would like to know any other multiple meanings to the word "a" in chinese.

Edit: Well, since i'm at school i can't delete this because the administrator won't let me...

Thank you!