Here we go&&Here you are

Explanation:
These phrases can be used in a manner of ways by different people but maybe this will provide you with a framework.

Here we go
discovery : here we go ex. finding something.
Here we go, I have been looking for my glasses all morning.
initiation : here we go ex. embarking on a trip.
Here we go, next stop the North Pole
presentation : here we go ex. serving food on the table.
Here we go, the tasty cockroach flambe you ordered.

Here you are
discovery : here you are ex. finding someone or something.
Here you are, I have been looking for you for twenty minutes.
presentation : here you are ex. serving food on the table.
Here you are, two vanilla cokes.