Move another object

how can i move another object than the one that contains the script? i’m using C#.
i’m starting in Unity, so i don’t even know how to call a GameObject from another script.
another question i have is how can i make appear an object in a determined position if i have never initially positioned it.

please have patience i’m new i this.

The index page of the Unity Scripting Reference has very relevant information:

There’s also a lot more goodies like these. If you’re starting with Unity, you really should get familiar with every references from the documentation.