Text Widget Social Media Icon links

(I have a child theme) I’ve added a widget area to my header and then managed to put a text widget in that area. I then tried to link media files from my library to show the icons in that widget area as well as have them link to the proper site. They are appearing as text links in the upper right hand corner rather than icon links. I’m sure I’m missing something obvious – probably I am linking incorrectly to my media files. I can’t find any actual step by step exact instructions for this. The site is: http://marginalia.wendywainwright.com.

My code in the text widget is:

<div id="social-icons">

<a href="http://wendywainwright.tumblr.com" target="_blank><img src=": http://www.marginalia.wendywainwright.com/?attachment_id=66"  width="48" height="48" alt="Tumblr" /></a>

<a href="https://www.facebook.com/pages/Wendy-Wainwright-Artist/151855994876474" target="_blank><img src="http://www.marginalia.wendywainwright.com/?attachment_id=63" width="48" height="48" alt="Facebook" /></a>

<a href="http://pinterest.com/wendywainwright/boards/" target="_blank><img src="http://www.marginalia.wendywainwright.com/?attachment_id=62" width="48" height="48" alt="Pinterest" /></a>

</div>