Hello,

For account report code in your xml file :

<?xml version="1.0" encoding="utf-8"?>
    <openerp>
        <data>
            <template id="account.report_invoice_document">
                 Your Account Report 
            </template>
        </data>
   </openerp>

For Header Footer you have to do like this :

<?xml version="1.0" encoding="utf-8"?>
    <openerp>
        <data>
            <template id="account.report_invoice_document">
                <t t-foreach="docs" t-as="o">
                    <t t-call="module_name.extend_layout">
                        Your Report                
                    </t>
                </t>
            </template>
        </data>
   </openerp>

Now, Code for Custom Header and Footer :

 <template id="extend_layout">
    <t t-if="o and 'company_id' in o">
        <t t-set="company" t-value="o.company_id"></t>
    </t>
    <t t-if="not o or not 'company_id' in o">
        <t t-set="company" t-value="res_company"></t>
    </t>
    <t t-call="module_name.report_header" />
    <t t-raw="0" />
    <t t-call="module_name.report_footer" />
</template>

<template id="report_header">
    <div class="header">
         Your Report Header     
    </div>
</template>

<template id="report_footer">
    <div class="footer">
        Your Report Footer
    </div>
</template>

Hope this will help you..!!
Thank you !