Hi there,
I'm Cherrelyn and I'm here to help. To link your iPhone to your PC and back up documents, photos, and files please try to use a USB cable to connect your iPhone to your PC. On your iPhone, tap "Trust This Computer" if prompted. Open File Explorer > go to "This PC" > select your iPhone. You can now copy photos/videos from the DCIM folder. For full backups or documents, install iTunes for Windows, then back up your device through iTunes. To sync via cloud, install iCloud for Windows on your PC and sign in with your Apple ID to access photos, files, and more automatically.
I hope this will help and If you have any question p[lease don't hesitate to leave a comment.
Warm regards,
Cherrelyn