Como esta Ud. is asking "How are you?", so you can answer with how you are.
Estoy = I am -- so you should use it with one of the following adjectives or adverbs:
Correct spelling is: Quien eres? Como te llamas? Means: Who are you? What is your name?
eres eres
Eres means "you are". Such as "You are American" = "Eres americano/a"
In Spanish, "you are not" is translated as "no eres" (informal) or "no es" (formal).
de donde eres is where are you from
"¿Qué" is "what" and "¿quién eres tú?" is "who are you?" in Spanish.
Are you married or not?
eres carinoso
In Spanish, "eres gay" means "you are gay."
What are you? = ¿Qué eres?
Eres guapo! (for male) Eres guapa! (for female)
Eres el mejor / Eres el primero