How to set up tour Apple mac if you use a proxy Server that requires authentication.
From the desktop click on the Apple logo at the top left
And then choose System preferences
When the system Preferences page appears click on the Network icon
Then click on your Ethernet or Wi-Fi connection
And select advanced
Then click on the proxies button
Select Web proxy (HTTP)
And on the right hand side enter the proxy server address
And then the port number
Put a tick in Proxy server requires authentication
And type in your username and password
Then go over to Secure Web proxy and place a tick in the box
And again on the right hand side type in the Proxy address and port number
Choose Proxy server requires authentication
And type in your username and password again
When you have finished click on Ok
And then Apply
And close the System Preferences page.