Game Screen

The Game Screen
The map might look different, this is the special Halloween map.
This is basically what the whole game screen will look like. There is a lot of valuable information represented very efficiently so that you can get an idea of what's going on at-a-glance.

Top right
I added text over the image to explain what each icon stands for. FPS is short for frames per second, the higher this number is the smoother your game will run. Your connection will be displayed across these four horizontal boxes, the more these boxes are filled the worse your connection is. Having a bad connection or low FPS will make executing timed attacks more difficult.

Directly below this information is a small box that represents your team's total kills verses the enemy team's total kills.

Jumping down further we get to the mini-map.
Pressing the ping-map button will allow you to point your allies attention to a location on the map.
Being aware of the mini-map can and will prevent a lot of hardships down the road. The gray area is called the "Fog of war;" the fog of war is the section of the map that no allied unit can see into. When enemies are hidden in the fog of war it is best to play carefully.

The map will display all non-champion units as small colored dots. Champions will display large character portraits on the map so that you know where everyone is without having to divert your camera.

Another thing the map can display is the location and status of allied and enemy structures. Structures that have been destroyed will become gray on the map.

Clicking a location on the map, with your camera unlocked (hotkey y), will jump your camera view to that location. To return the camera to your location quickly you can press the space bar, or re-lock the camera.

left of the mini-map
All of these buttons also have easy to access hotkeys. For detailed stats you press C, for Options you press Escape, for the Score Screen you hold Tab, to toggle your camera-lock you press Y.
Press and hold Tab for this overlay.
The score screen is the ultimate spy tool. This allows you to see almost everything about everyone. This gives you a breakdown of everyones' personal score, their items and which summoner spells they're packing.

You can even see enemy information here. The only restriction is that you can only see an enemies items if they're in sight. If they enter sight and then go back into the fog of war, the items that are displayed are the items that were seen on them last.

Knowing which items your enemies are building can give you an advantage when deciding your own items. And knowing which enemies have the most kills can help you decide who to target when a team-fight breaks loose.

In the bottom left you can view your stats, gold and current items.
Each gray bag represents an item slot. As you purchase equipment or items you can drag-and-drop them freely between these 6 slots. Consumables and usable items (marked by a green border) can be clicked via the mouse cursor or by pressing the key bound to that item slot. The top three slots are 1-3, and the bottom slots are 4-6 on the keyboard by default.

For information about the stats please visit: Stats section. The Green button next to the gold will take you to the shop window.

Shop
For information about the shop please visit: Items

Skills panel
For information about the skills panel please visit: Champions and Skills

Health Bars

Health in this image is between 401 and 500
Over the head of every player you will see a health bar like this and it will be green for allies or red for enemies. Above the health is the player's summoner name, the big number on the right will display the champions current level, and health will be displayed in the center as blocks. Each block can display up to 100 health. The health bar will fill from left to right, and drain from right to left.

Directly below the health is the secondary bar. On most champions this will display mana, but for some this will display energy, or shields, or even nothing.