My question is regarding Asp.net C # and Sql server 2008

Question

i am working on windows application in database i have a table which has Invoice number which is a primary key and keep increments by one number or so, when ever a new record is added, so what i want is,

i have a form which requires invoice number to be loaded in that form when page load, and when the record is saved that invoice number to be shown in a message box,

Sir please help me to achieve this,

It will be great-full Sir.