"Ello" is used only as a subject in certain cases and for other gramatical structures (a few ones). By the way, the correct is "estoy
dentro", using "
adentro", "
afuera",
abajo
de", "
arriba
de" are typical mistakes made by native Latin American speakers. You add the "a" when moving from a place to another.
Voy adentro, voy afuera...
Encima de
Debajo de
Arriba de
Abajo de
A pleasure.