Just as your everyday exchange site works. You have 2 ways of doing this, either see the sell order by Alice and complete it by either "quick-buy" or by manually inputting your NEU/BTC ratio and quantity. Or by sending to Alice's address 0.1 BTC (BTC addresses can currently be managed by our wallet), and if she agreed to beforehand, she will manually send you her 1 NEU.

Fees will be 0.01% for any type of action.