once signed into my icloud how to access the files/photos?

On an iPhone you use the apps to access your cloud documents and data, the Photos.app to access photos and videos, Pages or Keynote or Numbers to *** iWork documents, the Files.app to access the items on iCloud Drive.

On a computer you can use the web interface at www.icloud.com to access your cloud documents and are not limited to specific apps. A web browser on a computer is showing you the Desktop version of www.icloud.com , while the iPhone will show you the mobile version, which is very different.

After signing in with Apple ID and password with account credentials and setting up iCloud Set up iCloud on all your devices - Apple Support and iCloud Drive Set up iCloud Drive on iPhone - Apple Support

To access the files see the article View and modify files and folders in Files on iPhone - Apple Support

To access photos set up photos Use iCloud Photos on iPhone - Apple Support

And view them View photos in the Photos app on iPhone - Apple Support