There seems to be a fair bit of wrongly-addressed posting at the moment.
[man]phpinfo[/man] will tell you what you've got installed on your system. Also you can use [man]function_exists[/man] on any relevant functions to see if they exist.
If you haven't got it there and you want to install it, the instructions (for installation and use) are in the [man]pdf[/man] or [man]cpdf[/man] sections of the manual depending on which PDF function library you want to go with.
As an alternative to that, there's something called FPDF, information about which can be found by searching these forums for that word (I forget the URL).