If you selected an empty block, delete all of the HTML code. If your block has content in it already, do not delete the code.
With ConstantContact still open, go to your FaithStreet online giving Promote page and copy the code for the button you'd like to include in your email newsletter.
Paste the code into the Code View window. If you have existing content in the block, paste the code where you want the button to show up (e.g. before or after your content). Click "Update".
Save your changes.
You're done! The button image might not show up correctly while you're in editing mode, so click "Preview" on the top right of your ConstantContact window to view your email newsletter with the Give Online button.