DV Claim? How does it work?

I was in an accident at the end of March and my car was in the shop for a little over 2 weeks. The other persons insurance claimed fault since the driver rear ended me. I was just recently told about DV claims and I feel like once I started researching them, I got all nervous and stopped lol. I planned on trading my car in next year before the accident even happened, but now I’m worried that it’ll really hurt my chances of doing that and coming out on the good side of things and that I maybe should contact their insurance computer to file one. Can someone explain how it all works in lemans terms? Like do I contact their insurance and just straight up say I want to file a diminished value claim?? I’m so lost, any advice will help!! lol