Not sure how much and what parts you want to wash out but you can call up the "hue & saturation" dialog box (Ctrl+U) and drag the sliders around (try the "lightness" slider first). The benefit of this method is you can edit the Master (which effects all colors) or you could select specifically the Reds, Greens, Blues, Cyans, Magentas, or Yellows.

I recommend making a copy of your layer first before experimenting as these are "destructive" edits (they actually modify the image). Or you can create an Adjustment layer (use the icon next to the Layer icon - the one that's a circle) and select the Hue/Saturation choice. This way any effect will happen to this layer and not to the actual image. Keep in mind this will affect ALL layers beneath this one.

one way out of many

:)
retrocity