That would be "Egy szép, fiatal nő fent van". But if you're not strict, just want to convey the same message, then it's ok.
Two thoughts. First, I believe 'ez' means 'this', not 'there'.
Second, remember that in English the word 'there' does not always refer to a spatial locaton. For example, 'There is something I want to tell you.' You can even see two different kinds of 'there' in the same sentence: 'There is a young woman there'. In that last sentence, only the second refers to a spatial location; the first is a kind of dummy or filler word to start off the sentence (like 'it is ...').
So be careful how you translate 'there'. Sometimes you don't need to translate it at all: There is a woman upstairs = A woman is upstairs.
Well, the word order of your suggestion is awkward in English. It would almost always be "pretty young". But yes, "szép" could be translated as "pretty".
In this case, does the verb "van" attach "woman" to "above" or refer to the existante of the woman? E.g
Van fent nő = Woman IS above
Van fent nő = There IS a woman above
And how do we distinguish between these two statements.