ALL INFORMATION YOU NEED IS EXPLAINED ON THE NOTES ON THE ITEMS, RUNES AND MASTERIES ETC FOR YOUR SIMPLE EDUCATION :D

YOU CAN THANK ME LATER :P

Basically Garen is this:
-Garen is a sustained dps fighter; he needs to be decently tanky for long term dps so build one of each type of resist item sunfire/deadmans/randuins with banshees/visage and the rest are usually damage items built around your laner and the enemy team.

Pros:
-Naturally tanky
-High base damage during laning phase and early game
-Scales into late game if built with enough damage items
-Melee carry
-Anti assassin champ
-Can kite certain melee champs due to his 175 melee range attack
-Hard to gank
-Concerning most melee champs, he will win the lane

Cons:
-If he doesnt snowball then become less usefull
-If he isnt built correctly when snowballed he will stall and fall behind
-Weak to kite
-Cant deal with cc very well
-Lacks engage
-Lacks cc

The last 2 points are really what make him better suited to the roll of a fighter melee dps rather than a straight up tank. If your team relies on you to engage and tank then your team is clearly ******ed, remember that. You should be the one rounding up both the damage and the durability however your emphasis should be on sustained dps output not tanking.

Remember if your a beginner or as a rule of thumb:

2 tank items (1 magic/1 Armour)

3 Damage Items (according to the situation at hand and for the enemy team)

1 Utility (boots)

choose these from the Options 1 and 2 in the above builds

You are the main man, you have everything the team needs to be rounded up in all stats. However your main priority should be diving carries and peeling assassins off your carries without being the front-line. For example, let a malphite engage then you should proceed immediately after, as you can immediately start your dps output whilst they are cced. Garen is an excellent anit assassin champ too. His counter is the perfect counter to the majority of all assassin champs you can think of.

REMEMBER! ITS NOT ALWAYS A GOOD IDEA TO ALWAYS GO FOR THE VILLAIN FIRST &
1. Let the proper tanks engage first, then follow up
2. Dive the carries
3. Aim for assassins when you see they will kill your carries
4. You are sustained dps, only reason why build tanky is you can dps longterm (build one of every resist tank item randuins/visage with 3 damage items will allow you to deal consistent dps and still be very durable.

Plz fill free to post your records of your games to me by simply linking them in the chat!

Heres one with my favourite Garen build:

http://i.imgur.com/J5xnpa0.png

Here are links to other amazing guides:
http://www.mobafire.com/league-of-legends/build/spin-to-crit-reborn-99504
http://www.solomid.net/guide/view/43750-garen-build-guide-fighter-by-marinerevenge

ALSO CHECK OUT MY SION GUIDE ON THIS SITE!

-Introduced a new counter item start for certain counter picks in the Your Victim and your fears section
(25/09/2015)
-Updated masteries and runes
(25/09/2015)
-Did overall check of guide
(25/09/2015)
-Rewrote guide
(24/06/2016)