Explaining the STO HUD

You can click the image to enlarge.

1. Your Current Rank and Grade. 10 skill bubbles = 1 grade. 10 grades = 1 rank.
2. Your Current Grade level in the gold bars.
3. Your Current skill points for the grade in the bluish-white bars.

4. The name of the current map you're on. If you click it, you'll get an option to change instances. This is handy in raid/random encounter areas to switch between maps. Also, good to switch to an instance of the map with the rest of your team.
5. Exit to sector/beam up button. This will be galaxy when you're in a non-sector space map. It'll be a double-headed arrow when you're in ground mode. Use these to exit maps if you missed the dialog box or want to leave a mission early.
6. Sensor sweep button helps you find anomalies (crafting materials) and mission glowies.
7. Mini map.
8. Hail Starfleet button to get more missions or turn in missions.

9. Your ship's throttle.
10. Power settings. This is how you can switch your ship into different modes. These power settings have major implications in space gameplay. So use them! There are four presets.
The X preset is an attack mode (100 in weapons, 50 in shields, 25 in movement, 25 in auxiliary).
The triangle in a circle preset is the defense mode (50 in weapons, 100 in shields, 25 in movement, 25 in auxiliary)
The double triangle is a speed mode (25 in weapons, 25 in shields, 100 in movement, 50 in auxiliary)
The equal sign is a balanced mode (50 in weapons, 50 in shields, 50 in movement, 50 in auxiliary)
11. Weapons systems. The three mini buttons are for firing all beam weapons, firing all projectile weapons and firing all weapons.
12. Bridge Officer powers. The powers available are based on consoles and officers.

13. THE ELUSIVE ARROW - This is ann additional submenu that gives you several important options. It's how you join PvP queues without being in the PvP sector, access your messages, bringing up the fleet window, visiting your ship's bridge and accessing the C-Store (which is where you need to go to get your pre-order bonuses).

Hope this helps.