get_post_meta

I am trying to use the get_post_meta(); tag. My post is set up right and <?php the_meta(); ?> returns normally.

The metadata is the URL of an image. I would like to provide a URL in an key called “thumbpost” for each post and display the image in the loop in an archive page.

seems pretty straightfoward (working off the kubrik template):

in the loop somehow: <img src=”[metadata thing]”>

will this work? how do i set this up? must be just one or two lines of code. I can’t seem to get it to work.