Create the straight wire, hover the mouse over the middle of wire, hold down the control key, click/drag the wire to create the curve. Doing this near the end of the wire will adjust the curve at that end.
If there are bends in the wire, each segment can be adjusted like that to create more complex curves. See the GND and 5V wires in https://wcrsyyc.github.io/ardx/circ11.html for and example. The Fritzing sketch is there to download.