I have some users listed below in an order:

user1
user2
user3
user4
user5

This is just a simple list, sorted according to age.

Now a new user (user6) comes in, and according to the sorting, he fits after user 2, so the order becomes like:

user1
user2
user6
user3
user4
user5

Now I want to know at which position it is. For example it is on place3.
How can i find its position when a new user comes in the list??
Please tell any general way?
there is no any database etc, just a logic question.