The Poser 7 tutorial manual goes way more in depth about the cloth room and the purpose of each function. But just remember while you are doing you construction of dynamic cloth that

Soft decorated Groups
Assign vertices to this group when you want them to flex and move with the underlying cloth. Such as belts, belt buckles and shoe strings. So in the cloth room you will see the button for Soft Decorated groups just select it and then the group box will pop open for you to select the areas that will belong to the Soft Decorated group.

Rigid Decorated groups
Theses are parts of the group that when you want then to move with the underlying cloth but they don't bend or flex. When these are usually your buttons and jewelry type stuff. And you would do the same for the Rigid Decorated click it and the group editor box will pop up for you to select the vertices for that group.

I recommend when modeling you outfits in whatever 3d app you already know what you want to do with each area and make the groups in the 3D App so when you pull it over to poser the groups you set in the 3D app will transfer over. And you can just select the groups that way when setting up.

Go to the cloth room hit whatever functions you are using and then select add a group and all the groups you made in your 3d app will appear for you to select and it will add your vertices that way. But the Poser 7 tutorial manual is more explanatory. But that is really all it is to it.