What is Inkscape?
Inkscape is a vector drawing program. You can create all sorts of graphic illustration, into a very efficient way - you can go back and correct or modifies every line you draw. It is a kind of procedural drawing.
Download it from http://inkscape.org/ and take a look here http://inkscapetutorials.wordpress.com/ to see what can be done.
Reference key http://inkscape.org/doc/keys045.html
1. To draw a bezier lines:
B - Bezier tool
Click -create a sharp node
Click&drag - create a nod with 2 handles
Shift+L -to create a corner node
RightClick or double click to end a line
Click to the end of the line (red node) to continue the line.
There are 4 types of nodes(control+click toggle them)- corner, smooth, symmetric and auto smooth
Visit this link to see what can be done with inkscape: