I need help customizing the rest of my book. I cant seem to find the settings that control the light gray area on the trade window of the top right area to match the rest of my color scheme. Perhaps someone might know?

Have you tried Sierra Chart documentation? They have comprehensive and detailed description for every option you looking for:

https://www.sierrachart.com/index.php?page=doc/ChartTradingCustomizingGraphics.php

Quoting 

I cant seem to find the settings that control the light gray area on the trade window

I think those colors are controlled by Windows.

Here are two threads about dark themes:
https://www.sierrachart.com/SupportBoard.php?ThreadID=33723
https://www.sierrachart.com/SupportBoard.php?ThreadID=41173

https://www.sierrachart.com/index.php?page=doc/ChartTradingCustomizingGraphics.php