To add the theme system wide(Reccomanded).

Using Ternimal

1. Download and extract the "Black-desktop-theme" folder(can be extracted to any location).

2. Open a terminal window in the "Black-desktop-theme" directory and enter the following command in the terminal

$ sudo cp -r DeepBlack McOS-MJV-Cinnamon-Edition-2.0 /usr/share/themes

3. Now open the System Settings, navigate to the Theme configuration settings and change the "Window boders" and "Controls" properties.

To add the theme to your system for a single user.

Using GUI

1. Download and extract the "Black-desktop-theme" folder(can be extracted to any location).

2. Go to the "home" directory and toggle on the hidden files as shown below.

3. In the "home" directory, find the hidden directory ".themes" and paste the DeepBlack and McOS-MJV-Cinnamon-Edition-2.0 folders in ".themes" directory as shown below.

4. Now open the System Settings, navigate to the Theme settings and change the "Window boders" and "Controls" properties, as shown below.

Using Terminal

1. Download and extract the "Black-desktop-theme" folder(can be extracted to any location).

2. Open a terminal window in the "Black-desktop-theme" directory and enter the following command in the terminal

$ cp -r DeepBlack McOS-MJV-Cinnamon-Edition-2.0 ~/.themes

3. Now open the System Settings, navigate to the Theme configuration settings and change the "Window boders" and "Controls" properties.

DEMO