GOT AN OPT IN BOX CODE – HAVEN’T A CLUE HOW TO PLACE IT ON SITE

I have a new opt-in box from Aweber. They gave me the html code for it. But I have noooo idea how to get it onto my site. Could you PLEASE help me do that today? My site is; http://www.your1stgarden.com/

I would love to have this box right exactly where that calendar is sitting. I am a MAJOR newbie so I need step by step non – tecki instructions. THANK YOU SO MUCH. This means a lot to me.
Claudia