。
We got a good spot for watching the parade.
Literal
We [topic-は] parade [object-を] see [purpose-のに] good position [object-を] secured.
のに marks the purpose ('for the sake of seeing'). 占める ('to occupy, to secure, to hold') is used here in the 'secure a position' sense — common with 位置 ('position, location'). A classic observation-event description.