Use the File... menu in Content Manager then. Choose 'Import content files...' and navigate to the location on your HDD/SSD that contains the .cdp and install them from there. Drag and Drop doesn't always work if you don't have your file extension associations up to date.
Use the File... menu in Content Manager then. Choose 'Import content files...' and navigate to the location on your HDD/SSD that contains the .cdp and install them from there. Drag and Drop doesn't always work if you don't have your file extension associations up to date.
You need to open up a File Explorer window and resize Content Manager to fit on your screen.
When importing content, I recommend changing Content Manager to show the Open for Edit screen. This will show any content that's been left open should you drag in something that already exists. You can then select the content, right-click and choose revert to original. You definitely want to do this if you've replaced built-in or DLC assets because that can cause weird errors that can't be easily found.