A dreamie is a villager that someone REALLY wants in their town.
To 'give' a villager, the villager you wish to giveaway to someone MUST be 'in boxes' as in, all of their stuff is packed into boxes. They are in boxes the day they tell you they're moving out, like Roscoe told me he's moving out on the 15th, if I time travel to that day, then he would be in boxes. After that, you open your gates and allow the person who wants your villager to enter and have then talk to the moving villager. The person will have an option of having the villager move into their town and they should accept. That's it!
Edit: sorry I forgot to include what this part of the forum means. 'Giveaway' in the villager section refers to giving away a villager to someone for free, usually done through a competition or a raffle.