Microsoft DirectX is not the one graphical API but the collection of different APIs to handle all tasks related to the multimedia, video and game development. DirectX exist only for the Microsoft Windows and cannot be used on MacOS or Linux without special software (Wine or Proton provide needed functionality but both translate DX calls to the native for the platform OpenGL of Vulkan API calls).
All DirectX components provide object-oriented design and operates with COM objects which is the layer of the cross-language abstraction and also exist only for Microsoft Windows.
For the graphical tutorial most intersting component of the DirectX will be Direct3D (D3D).
Here are tutorials for next versions of D3D: