Hey there!
I might have some difficulties explaining what my problem ist because im german and i use the german version of inkscape..
I have a photo where I then cut out a piece. That piece is all I need. How do i manage to get rid of that background which is still somewhere, so that I can use the bit that i cut out without all the extra data? the background still being somewhere messes with stuff i want to do to that piece afterwards. (oh god.. i dont think anyone will understand what i want..) please help...
thank you so much!
emEuk

If you just want the visual effect of cutting out part of the image then clipping is probably the answer. But this does leave the rest of the photo in the document, it's just no longer visible.

You could clip the image, then use Edit > Make a Bitmap Copy to get an image that only contains the part you've cut out. You would then delete the original from the document. This approach is not great, however, as making a bitmap copy in this way will likely involve resampling the bitmap image, which could result in a loss of quality.

Practically, the best solution is to trim away the excess parts of the photo in a bitmap editor prior to importing it into Inkscape.

are your sure you have to do it in a vectorprogram ?

its sounds like something i would do i Gimp

can you show us the picture ?