If you want to add your new block in all pages after the breadcrumbs:
1) app/design/frontend/{package}/{theme}/layout/local.xml
<default>
<reference name="root">
<block type="core/template" name="banman" template="banman/block.phtml"/>
</reference>
</default>
2) app/design/frontend/{package}/{theme}/template/page/1column.phtml
add this:
<?php echo $this->getBlockHtml('banman') ?>
after this:
<?php echo $this->getChildHtml('breadcrumbs') ?>
NB: If you want that your block will be just displayed in some page, the same thing but the xml will be changed like this:
<your_layout_handle>
<reference name="root">
<block type="core/template" name="banman" template="banman/block.phtml"/>
</reference>
</your_layout_handle>
EDIT
To display your block with a condition configuration, you have to add your config field in system.xml
a multiselect choice to tel to Magento in wich page you want to display your block something like this:
<fields>
<displayblock translate="label">
<label>Where you want to display the banman block</label>
<frontend_type>multiselect</frontend_type>
<source_model>yourmodule/system_config_source_view</source_model>
<sort_order>40</sort_order>
<show_in_default>1</show_in_default>
</displayblock>
</fields>
You have an exemple here
NB: Dont forget to add this in app/design/frontend/{package}/{theme}/template/page/1column.phtml
if(Mage::getStoreConfig('section/group/field')){
<?php echo $this->getBlockHtml('banman') ?>
}
EDIT2:
how to insert my block without changing local.xml
Go to your phtml where you want to display your block and add this, you dont need with this the xml
<?php echo $this->getLayout()->createBlock('core/template')->setTemplate('path_to_your_block')->toHtml(); ?>
You can set the createBlock('block/type')
with your block type.