Placing a Sphere in the viewer
Place a sphere anywhere in the scene
Place a sphere at the origin
There are special handles available at the geometry level for the sphere object that allow you to stretch and squash it.
Move to the geometry level by double clicking LMB the sphere node in the network editor or by clicking the Jump to Operator button on the operation controls toolbar.
Drag the handles to squash or stretch the sphere.
For specific parameter help see the Sphere node help.