Urgent Help me! XML and DTD problems!

[rachelt]

Hi, i'm rachel and i'm a 2nd year student in communications.

I have a problem, i'm getting errors when trying to preview my work in a browser.

I have no css yet but have the xml and the dtd.

this is my xml

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<!DOCTYPE musicbidding SYSTEM "musicbidding.dtd">

<musicbidding>

<header>CD Bay Incorporated Music Bidding</header>

<genre>Pop Music</genre>

<artist>
<firstname>Amy</firstname>
<surname>Winehouse</surname>
</artist>

<album>Back to Black</album>

<label>Island</label>

<price>£7.98</price>

<delivery>Free UK Delivery</delivery>

<seller>
<firstname>Ted</firstname>
<surname>Kord</surname>
</seller>

<phone>0191 200 3456</phone>

<mobile>07564 33333</mobile>

<description>
Amy Winehouse's second album, Back to Black,
is one of the finest soul albums, British or otherwise,
to come out for years. Frank, her first album, was a sparse
and stripped-down affair; Back to Black, meanwhile, is neither
of these things. This time around, she's taken her inspiration
from some of the classic 1960's girl groups like the Supremes
and the Shangri-Las, a sound particularly suited to her textured
vocal delivery, while adding a contemporary songwriting sensibility.
</description>

and this is my dtd

<!DOCTYPE MUSICBIDDING [

<!ELEMENT HEADER>
<!ELEMENT GENRE (#PCDATA)>
<!ELEMENT ARTIST (FIRSTNAME, SURNAME)>
<!ELEMENT ALBUM (#PCDATA)>
<!ELEMENT LABEL (#PCDATA)>
<!ELEMENT PRICE (#PCDATA)>
<!ELEMENT DELIVERY (#PCDATA)>
<!ELEMENT SELLER (FIRSTNAME, SURNAME)>
<!ELEMENT PHONE (#PCDATA)>
<!ELEMENT MOBILE (#PCDATA)>
<!ELEMENT DESCRIPTION (#PCDATA)>

]>

can anyone help me please! i just don't understand.