In MMF2, you use the layers function to achieve parallax:
Basically add one layer for each part of your parallax component, and in the properties dialog, you can edit the layer's "scrolling coefficient". Make it >1 for a quicker scroll (ergo front elements), <1 for a slower one (elements in the back).
http://www.clickteam.com/website/usa/img/uploads/tutorials/download/scrolling_tutorial.pdf This clickteam tutorial covers the basic of scrolling and parallax.
I also read there's a "parallaxer object" extension, but I dunno what's the advantage it has.