Hi every on  can someone tell me how to put z value on a planthank you in advence.config: win XP autocad 2006 LTversion

You can't. Autocad LT has no 3D environment.

AutoCAD LT has limited functionality in 3D. But you can assign the Elevation and Thickness values to 3D entities - see e.g. the Properties palette (Ctrl+1).
 
See also LT vs. full AutoCAD