Hopefully it will Autodetect. If not go into ATI Control Centre. (Right click empty desktop)
Sound should also be on HDMI. See Control Panel/Sound/Manage Audio properties before you go out. Worst case is a 3.5mm cable from headphone jack to input on your TV somewhere. And perhaps some buggering about.
Don't pay a fortune for HDMI cable. Check Poundshops/local elec stores. Supermarkets/computer stores are expensive last I looked.