If you're prompted to back up your important folders (Desktop, Documents, and Pictures), select the prompt to start the folder backup wizard.
If you didn't see the prompt or you already closed the wizard, select the white or blue cloud icon in the Windows notification area, and then select Help & Settings > Settings, then Backup > Manage backup.
In the Back up your folders dialog, make sure the folders that you want to back up are selected.
Select Start backup.
You can close the dialog box while your files sync to OneDrive. Or, to watch your files sync, select View upload progress. If you already closed the dialog, to open the OneDrive activity center, select the white or blue cloud in the notification area.