Step 1:

To access the File Manager, log in to your Plesk Control Panel.

Step 2:

Click on ‘File Manager’ icon.

Step 3:

This shows your website’s directory structure.
Generally, files to be viewed by users are placed in the ‘httpdocs’ directory.
Click on ‘httpdocs’.

Step 4:

Click on ‘Add new file’.

Step 5:

Important: Select ‘upload file’. This is not selected by default.
Now click ‘Browse’.

Step 6:

Choose the file on your PC that has to be uploaded.

Click open.

Step 7:

Click ‘OK’.

Step 8:

Look for message ‘File was created’.

Step 9:

Scroll down the window and you will find the file that you have uploaded.
Logout of Plesk Control Panel after you have completed uploading all the files.