I am trying to get a quest to set to a stage once the player kills a PC, but i am having trouble. I am a noob at scripting so any help will be appreciated.
The character whose death is to trigger the update needs a script. Make it an Object script with an OnDeath block and apply it to the NPC character. You should be able to find many examples in the vanilla game to copy from. You'll possibly want to test a few extra things, to make sure the player was responsible for the death, that it happened at the right time etc. if that's important to your quest. The DB quest line is full of examples, all a bit different.