Front Panel Connectors are come with cabinet. These connectors are connected to Motherboard.
Front Panel Connectors are Power SW, Power LED, HDD LED and Reset SW. In Assembling process These connectors are connected to motherboard pins. There is a front panel pins on motherboard.
Here is the chart to connect front panel connectors. 6 and 8, both pins are power sw pins. so you can connect power sw to 6,8 pins. Power LED connector has two wires. 2 and 4 pins are power LED pins. so you can connect 2,4 pins to power LED. but LED has + (plus) and - (minus) pins. 2 is +(Plus) pin, 4 is -(minus) pin. so you can connect power LED green wire to pin 2, white wire to pin4. Pins 1 and 3 for HDD LED and pins 5 and 7 for Reset SW.
Latest motherboards have On board speaker. so no need to connect speaker. but old model motherboard and systems have speaker and speaker pins. speaker pins are near to front panel connectors. it is a four pin connector.
For more details refer motherboard manual.