When an offer is accepted, it is understood that both parties agree to ship items to each other immediately. You should have ordered your shipping supplies prior to adding an item to your store.
After both parties have accepted the swap, confirm the swap by messaging the other swap shop owner letting them know you are ready to ship. Shipping information, Tracking number, and other details will be exchanged through private messaging.
Do not ship your item(s) until you have confirmed with the swap shop owner that they are shipping their item as well. Make sure you ship to a confirmed address to help reduce chances of fraud.