Go to Viridian Meadows > Esior's Haven > Town Barracks. There, you choose the mission you want to send your pet on by clicking more info. Take note of the level required by the mission, and the main stat needed. Choose your pet from the drop down list, and send your pet on the mission.

Your pet will not be able to do any other activity during the time it is on the mission. Once the mission is finished, go to the mission log (under explore tab), and complete the mission.


Here's a guide on missions that'll be a good read: https://www.sylestia.com/forums/?thread=12841