elevation line specs

[celestep]

Hi

I am trying to understand elevations. I have been thru all the videos and the manual and the help buttons. I select terrain, elevation data, elevation line and then draw a line
I open it (I have used all methods) I then get the line spec box not the elevation line spec box.

I have an urgent design to do and a major headache, so I am on drugs and a little fuzzy, all I am trying to do is to create an area at the very back of the property that is divided off with a retaining wall and sits 650mm higher than the rest of the block and 2 meters deep (garden bed). at this 2mtr mark is another wall part retaining and part the neighour fence..

Can any one help

thanks
Celeste