Click the Grid Editor | Tools | Select command or the 
button to select individual grid nodes in the grid editor. The cursor changes to a crosshair 
when Select mode is active. The active grid nodes is indicated by a red diamond. The active grid node's grid coordinates are displayed in the status bar. Press ESC when in a different tool mode, such as Eraser, to quickly return to select mode.
Select a different grid node by clicking the node with the Select tool or pressing the ARROW keys.
Z Value Box
The Z value box in the tool options bar at the top of the grid editor window displays the Z value for the active grid node. Type a new value in the Z value box and press ENTER to change the grid node value. The Label, Node, Contours, and Color FIll display updates in the grid editor once you press ENTER or select a different grid node. Press ESC while editing a value in the Z value box to cancel the change.