I'd like to put an svg object over a picture I have. The latter is a .png file though I can change to gif/jpg as necessary. I would then like to alter the translucence of 1 or both objects (ie. how see through they are).

Any idea of how?

click the object you want to make transparent.
launch fill & stroke dialog (shift ctrl F).
set opacity.

Thanks; I didn't look hard enough!