@Moini: Amazing! This is exactly what I need. Thank you very much!
@Xav: Thanks a lot for the explanation.

THX for the answer. Hope I undertstand you but I do not know how is it possible to draw the outline of the whole drawing. My drawing consist of oval, bezier curves and straight lines. How can I make the single object (without inner lines) from this drawing?

Hi, I am new to inkscape and cannot figure out how to fill the object made of circle and few different pathes. I converted circle to path and then selected all and did Combine path. But if I try to fill it with color, it does not work... I tried to Join the nodes but T shape joints are not possible....