how do you give gifts in dragon age 2?

Answer 1

Each character has a specific 'gift' item that be granted to them. When you find it, you'll have an additional quest available for that character. Just go talk to them and the conversation will ensue.

Answer 2

You'll be tasked a quest after getting the gift, so you'' have to go talk to the person and he'll give his regards on his/her thoughts of it.