If you want a forum embedded on your Weebly site and you need a quick solution, register at http://www.lefora.com/ and create a forum there.
Contact the help desk via this link: http://support.lefora.com/support/tickets/new and ask for an embed code. You can get your forum embedded on your Weebly site and up and running in minutes.
Here is an example of an embedded Lefora forum on a weebly site:
This is just a test forum, so no huge activity there, but you get the drift :)