alt+left mouse button=rotate camera
alt+middle mouse button=move camera front to back
alt+right mouse button=move camera side to side, up and down
If you want the camera to view the planet at precisely 90 degrees, you can also double click on the camera and type in 90 in I think it's the x rotation input field (which would be the one on the left) and 0 in the y rotation input field (the one in the middle).
QuoteI can use either Terragen 2 or Terragen 0.9.
Terragen 2 is vastly superior for doing...well, everything, actually, but especially landscapes on a continent scale because you don't have to deal with the black edge of the world and stuff like that.