[kramarczyk]

NX Assemblies... (note I am using NX5, so instructions may not be 100% accurate)

A. Turn on assembly functionality in modeling. It can be found on the Start button.

B. Turn on the assembly toolbar if it does not default on. Tools -> Customize (mine is shown at the bottom of the screen) Alternatively you can use the functions under the Assembly option in the menu bar.

C. Add components - Assemblies -> Components -> Add Components
F1 should get you detailed context relevant help if you need it.

D. Constrain components - Assemblies -> Components -> Mate Component
F1 should get you detail context relevant help here too.

Spoiler for ***Warning***:

Constraining components will require an understanding of degrees of freedom. Not understanding this concept of defining the location of a rigid body with 3 translations and 3 rotations can lead to a lot of frustration. This is not a NX thing, it is a life thing as it occurs both in the virtual world of CAD and the physical world of actually builing stuff.

That should be enough to get you started. If you need more guidance feel free to post, PM or e-mail me.