It is in the vertex modeler, animation tab, then there are tools along the top. The usefulness and some details depend on if the the figure is rigged using legacy Poser (eg. Aiko 3, Vicky 4, Poser 4,...), Daz Studio Genesis generations, native Carrara, etc.

Here is the millenium subdragon which I believe has the same rigging type as Aiko3, V4, etc. I select the actor level, enter the vertex modeler, then in the upper right properties tray of the vertex modeler there are three tabs, click the center which is the animation mode. The weightbrush is available in the top menu now. Select a body part and weightpaint. Or, instead of the weightbrush, select a specific vertex or multiple vertexes and use the bone tab to adjust bone influence using the properties tray.