To post a YouTube video, first sign in to your YouTube account. Then, click on the "Create" button at the top-right corner of the homepage. Select "Upload Video," choose your video file, and fill in the video details (title, description, tags). Set your privacy settings, choose a thumbnail, and add any necessary video elements. Finally, click "Publish" to share your video with the world! Remember to keep your comment under 80 words for brevity.