Set a face as horizontal


Hey everyone,
I’am quiet new to the 3ds max world
I have some terrain models that i import into 3ds max. But their orientation seems to be broken, the terrains lean on the 3 axis.
In order to correct that, i’m searching for a 3ds max feature that could rotate a face of my model ( a face that i know that must be horizontal) on a reference face which is horizontal in my scene ( the face of a box for example) but i don’t get a proper result (may be a bad action from me)
I’ve created a box that i 've moved near my face that i would like to set horizontal [image 1]
After using the Alt+A shortcut for the align tool [image 2] my reference box doesn’t align with the terrain [image 3].

Do you have any advice for this procedure or other procedure in mind that i could use?
Thanks in advance


use normal align tool


thanks, i will give a try to it