Shortcut key to make my macbook sleep?
Putting your computer to sleep

Above is how to sleep your computer when it's on and logged in.
The keyboard shortcut is: ALT/OPT + CMD + Eject(i.e., ⌥ + ⌘ + ⏏).

Putting your display to sleep

Above is the keyboard shortcut for putting your display to sleep. The computer itself will not go to sleep, only the display will power off.
The keyboard shortcut is: Shift + Ctrl + Eject (i.e. ⇧ + ⌃ + ⏏).


Note: Computers that lack the Eject key
For computers that lack the ⏏ key – e.g. MacBooks – the Power key (⌽) can be used instead.
Also, it's possible to hold down the Power key for 1.5 seconds and then select from a menu if you want to Sleep, Restart or Power off. You can also access the menu immediately by Ctrl + ⌽.