Your Steam ID is a unique identifier for your account:
Open Steam and click on your username in the top-right corner.
Select "View my profile".
In your profile URL, the long number at the end is your Steam ID.
Alternatively, you can find it by:
Clicking on "Friends" in the top menu.
Selecting "Add a Friend".
Your Steam Friend Code, which appears here, is linked to your Steam ID.
For more details, refer to Steam's FAQ on Steam IDs.
If you encounter further issues or have questions, feel free to contact our support team for assistance.