Hi Debra,
I have the same answer as Lori, When I talk about Tromp as Writ, I'm talking about going across the warp and first dealing with the Olive/Peacock block, and then the Gold/Apricot, the Purple/Navy and so on.
So, if you are now looking at the Red/Pale Orange block and you want to weave red on top, look at your cloth to see what is happening, If you step on the first B treadle and the top layer is raised, and the red threads come up, then use the red shuttle for this pick, then the next pick is orange, then red then orange. This will give you a solid red on top, and a solid orange on the back side. If, however, the orange thread comes up as a top layer in your block, then you will use orange first, and red second. This will give you a solid orange on top and solid red on the bottom.
If, for some reason, when you step on your first treadle and three threads come up in the red/pale orange block, that means that this pick will weave on the bottom layer. So, step on your second treadle and see which colour comes up as a single thread, which indicates the top side. If this is red, then red is your second pick and orange is your first pick.
so, in this case you will weave orange/red/orange/red.
I hope this helps.