Info of InDesign's transparency effects are here: Transparency: Working with Effects in Adobe InDesign CS6
And there's a bit of a walk-through here: InDesign Help /
Adding transparency effects
To simulate the shading down the inner margins of the page, you could draw a rectangular frame from the top to the bottom of your page, and position it so it sits a little on the inner margins of both pages of the spread (if using facing pages) or down the centre of your page (if not using facing pages).
In the 'Effects' panel change the blending mode from 'normal' to 'multiply', and change the transparency if you need to. Then in the 'fx' drop-down menu choose 'directional feather' because you will want to soften the left and right edges of your rectangle.
Hope that helps.
Object > Effects > Gradient feather