...
Click on the question you want to upload files to.
...
The question will open.
...
Click the Add a comment line.
...
Click the Files & images icon.
...
Find the location of the file you want to add to your question from your computer, select the file and press the Open button.
The file you selected will be loaded.
If you want, you can add the additional message you want to convey to this section.
Click the Save button to complete the file upload to the current question.
...