On Magento 1x You can easily edit this area by going path app/design/adminhtml/default/default/template/sales/order/view/ and all of the admin order details content you get from here. Suppose i want to add a new block after Shipping AddressEdit area. For this i just open info.phtml.
Now just copy this line and past it again in lastly of info.phtml. Then go to your order you can see a block come
<div class="box-left">
<!--New address -->
<div class="entry-edit">
<div class="entry-edit-head">
<h4 class="icon-head head-shipping-address"><?php echo Mage::helper('sales')->__('Shipping Address') ?></h4>
<div class="tools"><?php echo $this->getAddressEditLink($_order->getShippingAddress())?></div>
</div>
<fieldset>
<address><?php echo $_order->getShippingAddress()->getFormated(true) ?></address>
</fieldset>
</div>
</div>
<div class="clear"></div>
After add this code you see new tab come but design broken for this you just need to go app/design/adminhtml/default/default/template/sales/order/view/tab path and open info.phtml
find <!–Payment Method–> by search then before this text <div class=”box-left”> tag you see just rename it to <div class=”box-right”> Done. You now see all tab very easily.
In the second part i will show how to add a image upload system before order place visit this link.