how i can create login for customer in silverstripe
It depends a lot on what you’re hoping to achieve. Silverstripe supports member authentication out of the box, so you just need to set up your users and groups, then set the permissions on the relevant pages and you’re done.
If you want something a bit more involved, let us know.
In the meantime, the CMS guide which covers things like users and permissions is here: https://userhelp.silverstripe.org/en/4/
There’s also some developer documentation about security, etc. here: https://docs.silverstripe.org/en/4/developer_guides/security/