Want custom field image to show with post titles and excerpts on archive pages

along with every post on a certain site i manage, i have a Custom Field name=“portfolio-image” and Value=“http://www.mywebsite.com/wp-content/uploads/image1.jpg

i want these images from the custom fields to appear on my archive pages along with each post title and excerpt.

this is the code from my category.php page: http://pastebin.com/Ap6Kt3Av. what do i put in there and where to make that happen? please advise. thanks in advance!