The Grand Exchange is a pivotal place in the Hub where players buy items using Dabloons. In order to use the Grand Exchange go to the central area of the hub Hub labelled "Grand Exchange". Speak with a business NPC by left clicking or tapping on them. This will open a UI which allows you to select the item you would like to purchase, and then further select the exact amount you want to buy and the amount of Dabloons you have to pay. To sell items on the grand exchange please check out the Ports page.
The Grand Exchange can be accessed in the most central area of the Hub.