How to generate a Unique Code for Barcode Programming

Hello All,

I want to get a Unique Code to Generate a Barcode App for my 40 Users. Its a WPF(Form Based) application developed with C#. I want to get a random number of 10 digits that i can use for each user individually(means they have to generate it on their own PC and not by Server)

Thanks

Jazaib Hussain