I never realy fully understood what exactly is in a controle deck,..... can someone enlighten me?.

a deck that controls, near totally, an aspect of your opponent's hand, deck, etc., I think.

It depends on the type of "control" you want...there's hand control, field control and, sometimes (for me anyways), Graveyard control or Deck Control...

Hand = things like Spirit Reaper, Don Zaloog, White Magical Hat, Robbin' Goblin, Mefist the Infernal General, Confiscation, etc for discarding and decreasing your opponent's hand size and/or Airknight Parshath, Masked Sorcerer, Dekoichi the Battlechanted Locomotive, etc for drawing to increase your hand size.

Field = Zaborg the Thunder Monarch, Mobius the Frost Monarch, Ojama Trio, King Tiger Wanghu, Ground Collapse, Ojama King, Dust Tornado, Mystical Space Typhoon, and other things to either build up your own field and/or keep control over the opponent's field as well.

Graveyard = basically just removing things from play with things like Soul Release, Kycoo the Ghost Destroyer and such.

Deck = Deck Destruction pretty much.