Probably your home theatre will be having RCA input at the rear of the box , RCA (google for the image of rca cable) . If yes then you will need to get RCA TO 3.5 MM cable (3 in quantity). Connect RCA end to your home theatre , check whether it goes to the rear speakers , centre/subwoofer speakers or front speakers , according connect to the matching slots. Your motherboard will need 5.1 audio support for the same