Well how to ?

I want an npc that reacts with custom dialogue whenever encountered , stuff like hello , how r u etc .. how to do that? I seen the quest dialogues but how to make the normal chat greetings?

Go to the MISC tab in your quest, and you add them there. They're Hellos and Goodbyes

I know that but I don't want to start a quest for saying hellos and goodbies .... how I do without a quest ? why do guards and others do it even if I place them in my mod without the need of a quest?

All dialogue is handled by quests; that's just the way the game engine works.

Your guards and such have those topics because there are default quests in the game that have default dialogue for NPCs in certain factions, like guards.

like wich ones ?What are the qests that start from very beginning of the game and never end?

- DialogueGeneric
- DialogueGuardsGeneral

and dozens of other quests with an editor ID starting with ''Dialogue''

Ok so to make it work for my own mod do I need to add my guards to this quest , OR make another quest? with my guards? what if I do not wnt guards to use other speech if not the normal beth one?

And how do you change a quest for your mod without changing the vanilla quest?

I recommend if you have your own guards, just creating your own quests. I have factions for dialogue (i.e. FalskaarGuardDialogueFaction) and then I have a guard dialogue quests, which I've jam packed with the guards combat, detected, and misc lines. If you're adding a few 'vanilla' guards to a mod then use vanilla ones. If you're adding your own guards to a brand new land (Like you are, Prometheus) then make your own quest.

I also have seperate quests for my own characters, guards, bandits, necromancers, commoners, and more. That way I don't touch the vanilla systems, and I don't have people in my land talking about events in Skyrim that they couldn't possibly know about.

Right thanks ....