Hello @CarolynY5 !
After doing a bit of research it looks like right now the only Retargeting ad Pixel tool we offer is for the shoppable landing pages. We are still working on this for other areas of Constant Contact including emails. It is something we have spoken of adding into emails in the future but for right now here is some information about shoppable landing page to use the retargeting pixel.
We apologize for any inconvenience this may have caused.