Hello everybody i am very new in using inkscape and i wanna ask something for example i import a png file into inkscape after that i want to get just a determined place on it how can i do that ? especially to create phone icons

Welcome to InkscapeForum!

I'm not sure if you may have used a translator so you can post the message in English? This part did not translate very well:

" after that i want to get just a determined place on it "

Or if it's not a mistranslation, can you explain a little more what you need? It sounds like you might want to isolate something from the PNG, to be used as a phone icon. If that's the case, you might want to use a raster graphics editor (such at The GIMP). That's because simply importing the PNG into a vector file does not automatically change it to vector. However, you can change it to vector, using Path menu > Trace Bitmap. Then you can delete everything except the part you need. A little node editing might be needed, so it's probably not quite that simple.

Having said all that though, it might be better to draw from scratch, an icon meant for a phone, rather than trace a raster image, and extract the portion you need. I guess tracing could work, but it depends on the original image.

Let me know if I've misinterpretted your question