My  baby belly button pop out not going in ...

Hai Tanu, Please don't try to push or put too much pressure on that part. Every kid have a pop out belly baby is attached from there to mother . As baby will go back. That part should dry properly. Just dab with towel after bath.

It too early wait nd relax give yr body time it take 6 month to recover properly if natural delivery than start walk nd little workout if doc allows from 4th month nd of c session than wait for 6 month than with doc green signal go ahead
as of now avoid fried food, too oily spicy food , have balanced diet have eat fresh home made food

It's normal, don't put pressure gradually it will go in.