how to display invoice -bill in a php site?

[eluser]harper23[/eluser]
Hello everybody

I am new to codeigniter, and not so new to PHP, I am developing a site that has a login for 2 users, and once they login it shows an optin to view an invoice-bill, I am not to making the invoice since 0, I have a stack of invoices, so I want to do it that once they click in view invoice-bill they can see a PDF. I have searched but I ask you for some idea in the visualization of PDF in codeigniter?? because you are the experts