Hey just started looking at XML, need some help with a schema I've been developing for a simple file. I think my problem comes from I don't fully understand how complex elements nest within other complex elements.

The XML file is basic like so:
Code:
<?xml version="1.0" encoding="utf-8"?>


<products xmlns="amazon" xsi:schemaLocation="amazon file://uadfil04/students$/0605353/My%20Documents/XML/XML%20Tutorial%20Project/TutorialProject/Schema.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance">
<item type ="Book">
<title>Harry Potter and the Philosopher's Stone</title>
<author>J.K Rowling</author>
<publisher>Bloomsbury</publisher>
<stock>121</stock>
<reference>65564134641323</reference>
<cover>  hello
<price type ="hard">10.99</price>
<price type ="soft">6.99</price>
</cover>
</item>


<item type ="CD">
<title>Sunny Side Up</title>
<artist>Paulo Nutini</artist>
<publisher>Sony BGM</publisher>
<nooftracks>12</nooftracks>
<stock>20</stock>
<reference>13156146133123</reference>
<price>9.99</price>
</item>

<item type ="Book">
<title>Glue</title>
<author>Irvine Welsh</author>
<publisher>Edipublish</publisher>
<stock>5</stock>
<reference>785123445123</reference>
<cover>
<price type ="hard">14.99</price>
<price type ="soft">7.99</price>
</cover>
</item>

<item type ="Book">
<title>The Da Vinci Code </title>
<author>Dan Brown</author>
<publisher>Corgi</publisher>
<stock>18</stock>
<reference>4561315646132</reference>
<cover>
<price type ="hard">6.99</price>
<price type ="soft">2.99</price>
</cover>
</item>

<item type ="CD">
<title>Which *****?</title>
<artist>The View</artist>
<publisher>Sony BGM</publisher>
<nooftracks>13</nooftracks>
<stock>9</stock>
<reference>782345643427</reference>
<price>7.99</price>
</item>

<item type ="CD">
<title>Sunny Side Up</title>
<artist>Paulo Nutini</artist>
<publisher>Sony BGM</publisher>
<nooftracks>12</nooftracks>
<stock>20</stock>
<reference>13156146133123</reference>
<price>9.99</price>
</item>

<item type ="CD">
<title>West Ryder Pauper Lunatic Asylum </title>
<artist>Kasabian</artist>
<publisher>Sony Music</publisher>
<nooftracks>15</nooftracks>
<stock>29</stock>
<reference>16574461354946</reference>
<price>11.99</price>
</item>
</products>
My XML Schema is like so:
Code:
<?xml version="1.0" encoding="utf-8"?>
<xs:schema xmlns="amazon" targetNamespace="amazon" xmlns:xs="http://www.w3.org/2001/XMLSchema"
  elementFormDefault="qualified" attributeFormDefault="unqualified" xmlns:jaxb="http://java.sun.com/xml/ns/jaxb">

<xs:element name="products">
  <xs:complexType>
    <xs:sequence>
                 <xs:element name="item" type="Book"/>
                             <xs:complexType>
                             <xs:sequence>
                                           <xs:element name="title" type="xs:string" default="N/A"/>
                                           <xs:element name="author" type="xs:string" default="N/A"/>
                                           <xs:element name="publisher" type="xs:string" default="N/A"/>
                                           <xs:element name="stock" type="xs:integer" default="0"/>
                                           <xs:element name="reference" type="xs:integer"/>
                                                       <xs:element name="cover">
                                                                   <xs:complexType>
                                                                   <xs:sequence>
                                                                                <xs:element name="price" type="hard"/>
                                                                                <xs:element name="price" type="soft"/>
                                                                   </xs:sequence>
                                                                   </xs:complexType>
                                                                   </xs:element>
                             </xs:sequence>
                             </xs:complexType>


    </xs:sequence>
  </xs:complexType>
</xs:element>

</xs:schema>
Someone told me I need to reference the complex elements and then call them in rather than declaring them inside each other but I can't seem to find an example of that maybe someone could point me in the direction of one?