smart watch notifications

Ok so i am building a smart watch and im wondering how sould go about if i want to have phone notifications on my watch... what i want is for my phone to send data to the watch when ever i get something such as a text ... what should i use for this i could use Bluetooth,wifi or what ever is small and workable

Ok, bluetooth.

Ok do you know if the Bluetooth library already has commands for that? Because i know i can send information using an app to the arduino but what about having it autonomously send data to the phone

I don't think there are any pre-existing libraries for what you want to do. They are written for modules that won't fit in a watch.