At the start of the level, you'll run across a couple paths. Don't worry about them too much as they lead to the same area a few inches later. There's a bridge to your right, but lowering that is no necessary.
You'll fight several monsters here and the most important thing that they drop is a cure orb. There's a chest near the coast. You'll then need to insert a circular key in order to open the bridge.
When you cross the bridge, you'll find a few small goblins and one giant one. You can open the next door with the key, but there's an area to the south you can explore. In this area, you'll walk through the beach shore and then up to a hill. Fight your way until you get to the top, where you'll find a chest. There's also a moogle house along the wall.
Now go back to the second gate and you'll come across two paths. Go to the right for now and fight your way to the chests. Then go back to the fork and go across the bridge over the river to arrive in the final area.
You'll be slicing enemies left and right here. There's a chest in the furthest left corner. Then go across the final bridge and under the rocky bridge to get the boss.
The boss for this level is a crab. He specializes in thunder magic as well as slow. He will do a two-part pattern of either smacking you or bubbling you. As you hurt him, he loses parts, but he has new abilities. Try not to get caught in his thunder. Soon, he'll be down and you'll get fresh loot.
I suggest the moogle pocket, if it is your first level. Having flexibility is always a good thing.