This might vary based on the version of code you're running, but under the Wireless LANs section, you can select your WLAN you wish to make these changes to. Go down under Advanced Options. From there, the L2 Access Control Service is where you'd apply a MAC filter (since MAC addresses are layer 2). There's a radio button there to either allow only these MACs or block only these MACs. Further down in the Advanced Options is the option to "Hide SSID - Hide SSID in beacon broadcast (closed system)".