Newbie to libgnomeprintUI

Hi All,

I am new to libgnomeprintUI and I was trying to develop an application
that would call the libgnomeprintUI when anyone wants to print through
my app.

However I am now facing some issues.

The first parameter to gnome_print_dialog_new(...) is GnomePrintJob
which contains a member guchar* input_file. I think this is the
pointer to the name of the file. However when I do the following I get
an error:

GnomePrintJob *pjob = gnome_print_job_new(NULL);
pJob->input_file=(guchar*)"filepath/filename";

The compiler complains that this operation is not allowed. 

So  I wanted to know what is the way I can pass to the
libgnomeprintUI, the file I want to print. I even checked out the
GnomePrintConfig but could not find anything related to this.

Can any one share with me some sample code on how it has to be done or
provide me with a way to do it, it would be helpful....

Awaiting Replies,
Mohit