[Rusty]

Originally Posted by hola

thank you Rusty. so what did i ask her?

The aquí antes (here before) part of your question was understood, and the girl may have deduced the correct meaning from that context alone.

Just so we're on the same page, have a look at the verb chart for ser. Find block 7 (Imperfecto del Subjuntivo). Fueras is a subjunctive mood, imperfect tense, second person conjugation.
Now scroll up to block 2 (Imperfecto del Indicativo). Eras is an indicative mood, imperfect tense, second person conjugation. This is closer to what you need, but the verb isn't correct.

Now have a look at the verb you should have used - estar. Look in block 2 (Imperfecto del Indicativo). There you'll find estabas.

It's difficult to say what the girl in the supermarket 'heard,' but I think she understood you.

There is no real translation of what you said into English. The subjunctive was used instead of the indicative. This mood has almost disappeard in English, but it has perfectly good uses in Spanish and must be learned.
The subjunctive can appear at the beginning of a sentence, where it takes on the idea of 'wishful thinking'.

If only you had been here before, ...
Had you been here earlier, ...
= Estuvieras aquí antes, ...

Had you been from Mexico, you would have known him.
= Fueras de México, lo habrías conocido.

I used estuvieras in the first sentence to show you two of its possible translations. The verb estuvieras is subjunctive mood, imperfect tense, second person of the verb estar (to be located).

I used fueras in the last sentence to show you one of its translations. The verb fueras is subjunctive mood, imperfect tense, second person of the verb ser (to be from).