When you created a Classic Project, a .project file was created. The folder containing this .project file is your project root. Any HDL files you create or copy into this folder (or its subfolders) will immediately appear in both the standard VS Code Explorer and the Sigasi Projects View.
You can manage your project files using standard file operations in the VS Code Explorer. Right-click in the explorer to create new files or folders, rename them, delete them, and so on. All changes will be reflected in the Sigasi Projects View.
For many self-contained projects, simply adding your files to the project folder is the only step you need to take to populate your project. After this, you can proceed directly to library mapping. The more advanced methods described in the following sections are only needed if you have to refer to files outside your project folder.