Where is the code for Campaigns > add new > body of the Campaigns e-mail ?

when we go to admin section > Promotions > Campaigns > Add New

When we add a new Campaign, save it, when we write something in the body of the Campaigns e-mail, where in the code this body is being made ?

I checked Administration > CampaignsDetails.aspx.cs, but there is nothing in that page

i am looking for the code something like message.Body = Where we write in the Body of the Campaigns E-mail using Fckeditor.

Please Guide Me....