After you have installed the add-on you will find the tool located in the "N-Panel" in the "Shader Editor" view.
Below you will find a list of the functions of the different sections and buttons that it has.
Table of content
This is the most important section to make the add-on work. Once you installed and you are in a new scene, you will have to import the Smart Weathering node to add the different effects. You will only have to simply click on the button with the import icon.
Once imported it will look as disabled and a legend will appear notifying you if the SW node has been imported.
<aside> 📌 Important It is convenient to previously delete older versions of SW before importing newer versions. To do so go to the "Blend file" view mode, search for the "!Smart Weathering" node under the "Node group" section, right-click on it and choose delete. This will delete it from all the shaders you have previously used, and after doing so, the "Import" button will be enabled.
By doing this step you will ensure the SW will be deleted from your scene. "Missing group nodes" will appear in your scene replacing the SW node.
<aside> ℹ️ Info After doing so, you can now import it again and use the "Add SW" node. When adding the new SW node, it will delete the previous "missing node groups".
After importing it now you can add it to your shaders!
The "select the objects" sections give you some handy tools to easily select objects where to apply them.