An Quest card reads " look at top 3 card of the encounter deck. Reveal and add 1 those cards the staging area and discard the other 2 card." Do I have to resolve when reveal effect if one of this 3 card has one card whit when reveal effect ? Hope You get what I mean!

Well.... why not ?

Unless you are saying that only one of those 3 as a when revealed effect and it's one of the two you discarded. In that case, no, the only card revealed is the one you choose to reveal and add.

Yes, I missreaded the quest card. Thanks

Note that "Reveal and add" is an early writing mistake, when vocabulary was not very normalised. A card is revealed or added, and both have a different sense: "add" does not trigger "when revealed" whereas "reveal" does. Here "Reveal" would have sufficed.