1. Install and open the GoodNotes or Notability application on iPad.

2. Import the PDF or image file to be marked. You can import files through the file import function in the application or through other applications such as file manager or cloud storage service.

3. Open the imported file and mark it in GoodNotes or Notability.

4. In GoodNotes, you can choose appropriate colors and tools (such as pens, highlighters, markers, etc.). ) and use ApplePencil or finger to mark and write.

5. In terms of distinctiveness, you can choose appropriate tools (such as pens, highlighters and erasers). ) and use ApplePencil or finger to mark and write.

6. After tagging, you can save the file or export it to other applications for further processing or sharing.