Is there a way to detect if somebody presses the key 'E'?

You need to use a LocalScript to access the PlayerMouse Object, and then you can set up a KeyPressed Event and check what key the pressed.

http://wiki.roblox.com/index.php?title=PlayerMouse

There is a KeyDownevent Put a LocalScriptinside the StarterPack

Player = game.Players.LocalPlayer
Mouse = Player:GetMouse()

function PressedE(key)

end

Mouse.KeyDown:connect(PressedE)

Now the above code is only a way to start it off it doesn't have any relation with key e yet

Player = game.Players.LocalPlayer
Mouse = Player:GetMouse()

function PressedE(key)
    Key = key:lower() --I'm just used to doing this..I don't think you have to
    if Key == "e" then
        print("Key e was pressed")
    end
end

Mouse.KeyDown:connect(PressedE)

Now the above code detects that e was pressed and it prints to the output.

Here is it in other words:

The Player = a Local Player Mouse is Getting the Mouse

If the Key pressed is e then print to the output

If the the Mouse's Key is pressed it will connect the function PressedE. And that function detects if e was pressed. So that's basically how you do it. Sorry if it's a bit sloppy.

I'd be glad if this helped :)