it is easy but it depends how you need to adjust it. Basically there is a little thing on the derauiller where the cable runs into it. where the black housing of the cable ends, there is something called a barrel adjuster. Use this to tighten/loosen your cable tension. Also ther are limit screws. The limit screw are for the High and low gears they determine how far your shifter goes to the high parts of your casette and the low gears of your casette. Gear 1 being highes, and your last gear being lowest. You need to fiddle with these to get your shifting correctly working.