Help with TeamRaiser eCards on donation forms with donor information included

Hello, I am trying to set up an eCard option within my donation form as a field that appears when the in honorarium option is selected. I have the eCard fields added to my donation form but I'm not sure how to do this conditional dropdown. I also need help making the default message text include user-specific information: the gift amount. For example, I want the default eCard text to read, “Thank you for your gift of $X” (or, ideally a custom equation that calculates the number of trees planted from the gift so donation $ amount / $8). Does anyone have any advice? I'm not sure how to add HTML to the eCard form options, or should I do it in the stationary?