Is your logo originally a vector image? Or did you open or import a raster version of it?
If it started out as a raster image, you won't be able to make a transparent background with Inkscape. That's because Inkscape is a vector graphics editor. Instead, you should use a raster graphics editor, such as GIMP. (
http://tavmjong.free.fr/INKSCAPE/MANUAL ... phics.html)
If it's a vector drawing, you need to use File menu > Export PNG Image. (The canvas background must be transparent, which it is, by default....unless you've changed it.)
If it's a vector drawing,
and you copy/pasted the logo at any time,
and you're working on a Mac computer, you've run into
a long standing bug. Use Duplicate instead.
Here's a long but detailed tutorial about transparency:
http://forum.inkscapecommunity.com/inde ... article=14 Not all of it will be helpful for your situation, but your answer will be found there....except that I've already written everything you should need in this message....unless there's more info that you've left out here, then you should find this tutorial useful.