I followed the instructions on using the Firefox debugger in VSCode but nothing works, I don't understand! (I'm a beginner.)

I used the JSON script which is instructed on the extension:

{
    "version": "0.2.0",
    "configurations": [
        {
            "type": "firefox",
            "request": "launch",
            "reAttach": true,
            "name": "Launch add-on",
            "addonPath": "${workspaceFolder}"
        },
        {
            "type": "firefox",
            "request": "launch",
            "reAttach": true,
            "name": "Launch index.html",
            "file": "${workspaceFolder}/index.html"
        },
        {
            "type": "firefox",
            "request": "launch",
            "reAttach": true,
            "name": "Launch localhost",
            "url": "http://localhost/index.html",
            "webRoot": "${workspaceFolder}"
        },
        {
            "type": "firefox",
            "request": "attach",
            "name": "Attach"
        },
        {
            "name": "Launch WebExtension",
            "type": "firefox",
            "request": "launch",
            "reAttach": true,
            "addonPath": "${workspaceFolder}"
        },
        {
            "name": "Launch index.html",
            "type": "firefox",
            "request": "attach"
        }
    ]
}