Has the epub you want the DRM? or it is "DRM less"?
if Your ebook (epub or PDF) has DRM protection you have to follow the istruction on:
http://www.jetbook.net/adobedrm
otherwise best to contact Ectaco support.
In my experience I bought several epub and pdf (without DRM) from
http://www.packtpub.com/ and they works perfectly on Jetbook Color