Every registered user of Wikimedia Commons has a public talk page of their own where you can leave a message. If the user has specified an email address, you could also use the Email this user function (in the toolbox at the bottom left) on the user's page. This function is only available if you're logged in and both you and the user you wish to email have enabled email in your preferences.
කොමන්ස් සමඟ උදව් ලබා ගැනීම
Questions regarding the usage of Wikimedia Commons are best asked at the Commons:Help desk. Usually, you’ll find capable Wikimedians around, who’ll answer your questions.