You can check your captain's stamina and experience at Captain Profile and Captain's Info.
You can see how much more experience you need to level up, and more details at Captain's Info.
■ How to check Captain Profile
- [Main screen] > [Captain icon on the upper left corner]
* Blue bar on the lower left side of Captain icon: XP
* Green bar on the lower right side of Captain icon: Stamina
- [Main screen] > [Tap on Captain icon on upper left corner] > [Check stats on Captain Profile]
* Top blue bar : XP
* Middle yellow bar : Stamina
* Bottom green bar : Plunder Points