CSS - Help with Image Floats and Z-index for Wordpress page

I'm trying to get my page to look as such:


URL: http://7pwc.moshpitdigital.com/new/

This is what my html looks like:

[rev_slider about]
<div id="about-header"><img src="http://7pwc.moshpitdigital.com/wp-content/uploads/about-meet-our-docs-seven-peaks.jpg" alt="Meet the staff at Seven Peaks Medical and Wellness Center"></div>
<div id="about-content">
<div id class="staff-pics2">
<img class="alignleft size-medium wp-image-149" src="http://7pwc.moshpitdigital.com/wp-content/uploads/SP_Staff_Dr_Wells.jpg" alt="dr-jon-wells-seven-peaks-medical-wellness-93401" width="280" height="400" />
<img class="staff-header" src="http://7pwc.moshpitdigital.com/wp-content/uploads/staff-pic-header.jpg"/>
</div>
<div class="staff-bio2">
<h3>Dr. Jon Wells</h3>
<h5>Founder, Chief Chiropractor</h5>
<p>Welcome to Seven Peaks Wellness and Medical, where my vision for providing quality health care is met with a professional, knowledgeable, well trained team and a warm environment for your entire family. I am Dr. Jon Wells and my journey here began with a board certified degree from Southern California College of Chiropractic where I graduated with honors in 1990.</p>
</div>
</div>

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My CSS:

.staff-pics2 > img {
margin-top:45px;
z-index:1000;
}

.staff-pics2 > img.staff-header {
z-index:1
float:left;
margin-bottom:-105px;
}

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Couple questions:

1) Am I organizing/referring to my div classes correctly? I'm trying to assign the green header with it's own class I can have this appear under the staff photo. Not sure if doing this correctly.

2) I've been playing with the z-index in Firebug and I'm unable to set z-index values individually for the staff photo (.staff-pics > img) and the green header (.staff-pics > img.staff-header). It's only allowing one or the other.

3) I have the class .about-header which is giving me full width "Meet the Doctors & Staff" image on the this page: http://7pwc.moshpitdigital.com/about-us/, but not the new one. http://7pwc.moshpitdigital.com/new/

Any help appreciated.