[Theme: Singl] Trouble getting AWeber sign-up form to display

I have been trying to have an AWeber sign up form to appear on my site and have followed all of the instructions at AWeber, including using the plugin. However, there is no sidebar in the singl theme in which to add the widget, only Footer Widget Areas 1, 2, and 3 are available. I tried putting it in each but cannot make the form appear. I was able to place the javascript in the post itself and get the form to appear, but why doesn’t the other recommended method work?

I also tried this as a lightbox or popover, which is what I really want, but to no avail. I tried to insert the javascript into my home page post, but this did not work. What should I do?