Richfaces Plug'n'Skin - how to provide images?

Question

I'm trying to build a custom richfaces skin by the Plug'n'Skin feature. I've build the project with maven. (like its mentioned in the reference guide)

I've tried to use the xcsswich isn't supplied to my app - everything looks like default. So I switched back to normal css in my tab-panel.xcss. This works: Styles are applied but one issue which I can't resolve:

How do I provide images to my css classes?

Example of my tab-panel.css

<?xml version="1.0" encoding="UTF-8"?>
<f:template xmlns:f="http://jsf.exadel.com/template"
xmlns:u="http://jsf.exadel.com/template/util"
xmlns="http://www.w3.org/1999/xhtml"&gt;
<f:verbatim>
<![CDATA[
    .rich-tab-active {
        background-image:url(register_active_bg.png);
        background-repeat:repeat-x;
        font-weight:bold;
        color:#000000;
        border-top:1px solid #c8c8c8;
    }
    .rich-tab-bottom-line {
    }
    .rich-tab-disabled, .rich-tab-inactive {
        background-image:url(register_bg.png);
        background-repeat:repeat-x;
        color:#969696;
    }
    .rich-tab-header {
        width:160px;
        height:45px;
        line-height:43px;
        font-size:12px;
        text-transform:uppercase;
        text-align:center;
    }
    .rich-tabhdr-cell-active {
    }
    .rich-tabhdr-cell-disabled {
    }
    .rich-tabhdr-cell-inactive {
    }
    .rich-tabhdr-side-border {
    }
    .rich-tabhdr-side-cell {
    }
    .rich-tabpanel {
        width:818px;
    }
    .rich-tabpanel-content {
    }
    .rich-tabpanel-content-position {
    }
]]>
</f:verbatim>
</f:template>

I've tried to register the image in my resource-config.xml

<?xml version="1.0" encoding="UTF-8"?>
<resource-config>
    <resource>
        <name>register_bg.png</name>
        <path>de/bc/richfaces/images/register_bg.png</path>
    </resource>
    <resource>
        <name>register_active_bg.png</name>
        <path>de/bc/richfaces/images/register_bg.png</path>
    </resource>
</resource-config>

Answer 1

After recreating the skin project with a baseskin it worked out for me like in my question, I post it here once again for more clarity

<?xml version="1.0" encoding="UTF-8"?>
<resource-config>
    <resource>
        <name>register_bg.png</name>
        <path>de/bc/richfaces/images/register_bg.png</path>
    </resource>
    <resource>
        <name>register_active_bg.png</name>
        <path>de/bc/richfaces/images/register_bg.png</path>
    </resource>
</resource-config>