Block not appearing drupal 6.37

Hi everyone!

I was given this code:

<iframe frameborder="0" src="https://www.givengain.com/widget/en/campaign/12714/" width="400" height="400"></iframe>

to insert a widget onto our website using the block function, www.ikamvayouth.org on the left sidebar but it won't show.

I thought maybe it could be too big and tried resizing it. I have very basic (almost no coding skills) so I can't really see what I'm doing wrong. The widget that was there previously was written in php I think so I tried to convert the html to php online but that didn't work.
Please help.

Thank you