Hi,
You want to replace the designs that are currently there now on each of the features page?. For Ex: http://dialsource.com/features/#tab-id-3 on this page under the description, there is a design now in blue color, which you want to redesign is it. Kindly confirm.
thanks,
Jai

Yes, that is correct. 

please what do you mean by this : " we would like 3-D backdrops of MacBooks and iPads with a screenshot layered on top."

I apologize for the ambiguity. It means that we're looking for our screenshots photoshopped onto Macbooks and iPads.

This website has a couple great examples of this: http://www.domo.com/company/what-is-domo

230 designs in just 2 days, will the project owner able to check them all?