Put δεν directly before the verb and nothing else moves. Όχι is a different word - it is "no" as an answer, and it cannot replace δεν inside a sentence. Greek keeps double negatives: δεν έχω τίποτα is correct.
Examples
- Δεν είναι ακόμα μία.
- It isn't one o'clock yet.
- Την Κυριακή δεν δουλεύω.
- On Sundays I don't work.
- Όχι, δεν μιλάω γερμανικά.
- No, I don't speak German.
The mistake to avoid
Όχι answers a question; δεν negates a verb. They are not swappable.
Where this fits in
Numbers, days, time, Greek A1: Count, talk about days and months, give the time, and handle numbers in real situations.