To edit an ellipse or a circle first select it.
A selected ellipse
Drag any rotate manipulator 
to rotate the ellipse.
Drag any scale manipulator
to re-size the ellipse.
Drag the ellipse/circle to move it.
Ellipse Properties Dialog
You can also edit the parameters of the ellipse using its properties panel as shown below. To view the properties panel first select it.Then right-click on it, then select Properties Panel from the context menu that opens.
Ellipse Properties Dialog
X
The X coordinate of the center of the ellipse.
Y
The Y coordinate of the center of the ellipse
Width
The width of the ellipse.
Height
The height of the ellipse
Layer
Use this drop-down to set the layer for the ellipse.