i cannot sing in to icloud by my iphone

Do you see any error messages?

Take a look at this Apple Support article, maybe it will help you.

iCloud: If you have trouble signing in to iCloud.com

The iCloud website is not intended to be accessed by mobile devices (you are expected to use the apps). If you use the 'Request Desktop version' option you may be able to get into it, but you are likely to find that parts of it don't work: it uses advanced programming which mobile devices can't handle.