Please go through the below link for the web auth configuration and uses of it.
Please check the below link :
With WLC Release 7.0 and later, the feature webauth proxy redirect can be enabled in the global WLC configuration options. When enabled, the WLC checks if the clients are configured to manually use a proxy. In that case, they redirect the client to a page that shows them how to modify their proxy settings to make everything work. The WebAuth proxy redirect can be configured to work on a variety of ports and is compatible with Central Web Authentication.
For more details: