Updating Plesk Obsidian to the latest build is an essential step to ensure you have the latest features, bug fixes, and security patches. Here's how you can do it:

1. Log in to Plesk: Open your web browser and log in to the Plesk control panel using your administrator credentials.

2. Check for Updates: Once logged in, go to the Home tab in the left-hand menu. Under the Plesk Obsidian section, you'll see an option for Updates. Click on it.

3. View Available Updates: In the Updates section, you'll see a list of available updates. This includes updates for Plesk itself, as well as any installed extensions or components.

4. Select Updates: Check the box next to the updates you want to install. In this case, you'll want to select the update for Plesk Obsidian.

5. Start Update Process: Click the Install/Upgrade button. Plesk will now begin the update process. This may take some time depending on the size of the update and your server's resources.

6. Monitor the Update: You can monitor the progress of the update on the same page. Plesk will provide status updates as it progresses through the installation.

7. Completion and Verification: Once the update is complete, Plesk will notify you. Verify that the update was successful by checking the Plesk version in the control panel.

Please note that during the update process, it's a good practice to have a backup of your data, in case anything goes wrong (though the update process itself is designed to be safe).

If you encounter any issues during the update process, refer to the Plesk documentation or consider seeking assistance from Plesk support or a qualified system administrator.