Please Help Chef server error

Hi All, I am getting below error in Chef. Please help.

ERROR: CONFIGURATION ERROR:chef-admin-server is an invalid chef_server_url. The URL must start with http://, https://, or chefzero://.

Looks you need to supply a URL

where do i supply a URL? Please advise. Thanks

Wherever you supplied "chef-admin-server"

where is the location for client.rb file? Please help.