For anyone who doesn't know, this is Warwick. His hungering strike spell (or "Q" unless you have edited your settings) allows you to do damage and also heal some of what you did, it is very good in tight situations and when jungling or trying to get some life back after a fight when all that is left are minions. This spell uses ability power to do more damage. Your Hunter's Call (or "W" ulnless you have edited your settings) allows for you to increase your attack speed. This comes in handy for everything and works so well with his passive (which allows you to heal on hit almost like life steal but it is a set amount). One of Warwick's best abilities, Blood Scent. This ability costs no mana and can be turned off but should stay on unless you are trying to gank. This ability is one of the most unique abilities in the game (personal opinion) because when active this ability makes it so that when you have an enemy within it's range and they have 1/2 life or less, it marks them. This mark increases your movement speed for as long as they are in the radius (you can use this to run away from or toward enemies). No matter where they are in the set radius you can see them, this includes: jungling people, people you have weakened and are trying to get away from you, or people trying to hide in a bush to gank. As you improve this ability it makes it so that the radius of Blood Scent increases and also the speed boost you get will have an increase. Finally, Warwick's ultimate (or "R" ulnless you have edited your settings) this does a slight stun but hits the enemy dealing damage plus a percent of your total attack damage. This can be used to kill enemies or to help a friendly character to get away from an enemy. It doesn't do much against people that are tank built, but this does extremely well against people who are "squishy" (or that don't have much life).
That is the basics of this character and some tips on how to get the hang of him.

You use these runes because it seems to work very well. It reduces cool down and still allows you to do lots of damage. Because of the reduced cool down, you are able to use your ultimate move (the "R" key unless you have edited settings) and you can get the cool down around 60 seconds without the blue buff.

Pros:
You do lots of damage and you can get lots of kills (including steals since Warwick has one of the best ultimate moves for kill stealing).
If skilled you are really good against anything but a tank.
You can solo Baron around level 14 if you have up to your Black Cleaver or Phantom Dancer (or at least I can).
With the attack speed increases and all the damage you do you are able to heal with your passive and Hungering Strike ("Q" unless you have modified settings).
You will also receive a fair amount of life for using your ultimate and then you can use Hungering strike as soon as it is over to help heal you more or get that last hit on them to kill them.

Cons:
You don't have anything for armor as far as defending yourself from A.P. (ability power) or A.D. (attack damage) builds.
You do not have increased life so you cannot tank.

This build works extremely well with jungling. You have "Utility Mastery" from your mastery points which helps you keep the red and blue buffs, as well as Baron's buff. You might be able to get Hungering Strike first if you prefer that to start off if you choose to jungle, but you can do it just like this if you start with the dogs or something small.

Overall this is a pretty good build, so far I have liked how it works for me. I typically end up with a positive score as far as kills to deaths ratio goes and usually it is a pretty good one (average is a 2:1 k/d ratio)