Do you mean the content directories? The quick way to add them, if they already exist and are content installed manually or through Dasz Install Manager/Daz Central, is to right-click on the Daz Studio Formats top-level container in the Content Library and select Add Base Directory, then for Poser content right-click on Poser Formats and seelct Add Runtime Directory. In either case you want the folder that contains the Runtime and Data folders. You can then reload the metadata, for Smart Content, the Categories lists, and the presets tabs in settings panes, by opening the Content Library option menu (the lined button in the top corner, sometimes called the hamburger button), selecting Content DB Maintenance, and checking Reimport Metadata - another dialogue will open in which you can check user data (anything you had exported) and any or all products found.

Content installed through Daz Studio must, if you don't have a back up of the database, be reinstalled - you set the directory in Edit>Preferencs>Content tab>Content Directory Manager (you can also use that to add the regular content directoriesm, instead of the above method). If you select the folder that contained the previous Connect installs (the one that holds the /data/cloud/1_##### folders with the individual product data) then reinstalling should find the files, speeding the process (and reducing the bandwidth needed) compared to a new install.

You can, if you wish, select only some of the content directories previously used, or merge folders together - Daz Studio itself cares only about where the fiels are within the content directory, it doesn't care where the content directory is or what it is called; Install manager/Daz Central do, however, track the actual location starting from the drive identifier so that they can later remove the files if desired.