Many mods will direct you to install them in the 'override folder' of either the core program or the documents folder.
The specific destination location will be different depending on the type of mod and who made it. Left-click on the mod you've selected in the DAUpdater program and left-click the 'install selected' button. Alternately, you can left-click on the 'Select DAZIPs' button and navigate to the location of the mod's folder. Drag the mod's '.dazip' file into the DAUpdater window.
