Help with HTML code

Hello, I’m trying to add an embedded code for my Constant COntact weekly newsletter archive. I just know website basics, and I can’t figure out how to add it to the sidebar on my site (byalecharvey.com). I love the theme, by the way. I just have trouble with coding. Can you help? I click on Add HTML code and it doesn’t seem to do the trick. THanks for any help!

Alec
auburn84@gmail.com