Now

This word marks the beginning of a new part of the story. If your language has a word or phrase that does the same, you could use it here.

ark of God

See how you translated this in 1 Samuel 3:3. This is the a same as the "ark of the covenant of God" in 1 Samuel 4:3-4.

This refers to the temple of Dagon, the god of the Philistines.

"they were very surprised to see that Dagon"

The reader should understand that Yahweh had caused the statue to fall on its face during the night. (See: rc://en/ta/man/translate/figs-explicit)