cannot compile using gtk

[trout2 <trout2 advancenet net>]

hello:

 i have just installed gtk on my machine, and am trying to do the
tutorials. i am unable to compile the simple tutorial programs. the
following program:

#include <gtk/gtk.h>
 int main (int argc, char *argv[])
        {
        GtkWidget *window;
        gtk_init (&argc, &argv);
        window = gtk_window_new (GTK_WINDOW_TOPLEVEL);
        gtk_widget_show (window);
        gtk_main ();
        return 0;
 }

returns these errors:
/var/tmp/ccKQ22211.o: In function `main':
/var/tmp/ccKQ22211.o(.text+0xf): undefined reference to `gtk_init'
/var/tmp/ccKQ22211.o(.text+0x19): undefined reference to `gtk_window_new'
/var/tmp/ccKQ22211.o(.text+0x2a): undefined reference to `gtk_widget_show'
/var/tmp/ccKQ22211.o(.text+0x32): undefined reference to `gtk_main'

i'm afraid i don't know enough about gtk to see whats going on here.
i read through the first few pages of the tutorial, and it mentions the
following gcc command: 

gcc -Wall -g helloworld.c -o hello_world `gtk-config --cflags` \ `gtk-config --libs`

produces this error:

gcc:  -L/usr/local/lib: No such file or directory

what is "-L"?
any suggestions would be appreciated

-aaronp