Find the boat on your first visit
If the Training Area is missing from fast travel, walk to the Buddy Plaza. Find the small boat between the two Palamute statues, to the right of the Argosy, and use it to travel to the Training Area.
Once you have visited, the Village Map lets you fast travel there.
Set up your practice
Use the Item Box to change weapons. Talk to Sekirei the Trainer, or open Start Menu → Training Options, to adjust the training target.
You can practice with consumables, compatible ammo, coatings and phials without reducing your inventory. This rule applies to the Training Area, not normal hunting quests.
Practice your basic attacks, dodges and camera controls before starting a hunt. The Argosy and Meowcenaries dispatch menus are separate facilities; neither is the boat’s Training Area travel option.