I'm assuming you have at least a fundimental understanding of navigating 3dsmax, but this is generally a very beginner tutorial.

This tutorial is to explain how to use smoothing groups in 3dstudio max. You may have created a model and found that all of its faces were faceted and you wanted it to look smooth, without adding extra geometry using something like turbo smooth.

Lets say however, you also want some areas to have hard edges, and not just a smooth over the whole mesh. That is also possible.

First make sure you object is editable poly, expand to the sub-object level (so that you see the list that says Vertex, Edge, Polygon etc.) and choose Polygon.

In polygon select mode, scroll down in the modifier menu until you see Polygon Properties. It should look like the image below.

I've made a slightly curved plane that is subdived several times. I selected half the faces and set them to smoothing group 1. The other half I set to smoothing group 2. To do this, just click on the button for that group. A single poly can be assigned to more then one group. You could have it assigned to all of them if you wanted, there is no limit. But we only have the right side assigned to group 2, so make sure you deselect group 1 if it's selected already.

Right now there is a hard edge straight down the center of the plane. But lets say that I want the hard edge to follow this line instead -

To get the hard edge there, I assigned these smoothing groups -

Where a face is assigned both group 1 & 2, there will be smooth connections. Since two faces next to each other share a group, they smooth together. Where two faces next to each other have different groups, they have a hard edge.

So this is the final result.

I'm sure you're confused. Just try it out yourself and you'll get the hang of it.