Create or using some ftp client commader upload your css or js file to: for example "../YourTheme/Content/css/" folder.
Now Open your GrandNode solution or website (version without source code) in Visual Studio - Go to this location:
Now you can see most of the css and js files that have been implanted into your theme:
Adding your own files to theme:
1. Choose the file type you want to implement: "AppendCssFileParts" for css and "AppendScriptParts for js file."
2. This is where the file will be located. If it is "ResourceLocation.Head" then the file will be loaded in head tag. If it is "ResourceLocation.Footer" then the file will be loaded after footer tag.
3. The path to file