You can't connect two HDMI outputs to each other.
ARC has nothing to do with it.
Connect the PC to your TV with HDMI and if you have an HTS already getting sound from the TV the PC will do so as well.
PCs do not have HDMI-ARC.
DVDs do not have HDMI-ARC.
ARC is a way to get audio from a ARC enabled TV to an ARC compatible home theater system, avr, or soundbar without an additional cable.