How to prevent adding item to excel 2007 if it found before c#

I work in c# 2015 windows form

I have excel file 2007 name book 1 and sheet inside it name sheet 1

sheet 1 have two column

UserID

UserName

I need when insert new record from windows form c#

to check if the value of User Name found before show to client message tell him that Username exist before

UserID UserName

1 michel

2 marten

IF user enter in textbox value of marten then click button insert

give me message that this name exist before

using c# windows form

How to do that by c# if possible