To block someone on Snapchat, follow these steps: 1. Find the user you wish to block in your Snapchat chat list. 2. Tap on their name to open a chat with them. 3. In the chat screen, tap on the Menu icon, represented by three horizontal lines. 4. From the menu options that appear, select "Block." 5. A confirmation box will pop up. Confirm your decision to block the user by tapping on the appropriate button or option provided. By following these steps, you will successfully block the selected user on Snapchat, preventing them from contacting you or viewing your content on the platform.