Basically there are two different types of helicopters,the kind of those that have collective pitch and another kind of those that do not. Collective pitch is where the pitch of the main rotor blades may be simultaneously increased or decreased to change the amount of lift. This gives a quicker response to changes in vertical thrust as controlled by the pilot. Helicopters without collective pitch are traditional technology and no longer available. We would strongly advise against this type of model as we are sure disappointment would follow and we don't want to put anyone off the hobby!
There are many more moving parts in a collective pitch rotor head and thus, they are cost more. All current helicopters on the market today have collective pitch.
On a standard, collective pitch helicopter there are four controls and these are operated by five channels of your radio system. These controls are the collective pitch, the fore and aft cyclic pitch, the side to side cyclic pitch, and the tail rotor pitch. The collective pitch must also be coupled with the throttle of the engine so that when more load is put on the main rotor blades by increasing the pitch, more throttle is applied to help overcome the additional drag.
The left stick of your radio transmitter controls the collective and throttle in the vertical direction and the tail rotor pitch in the side to side direction. Your right stick controls both cyclic operations; up and down for fore and aft control and side to side for the cyclic side to side control. There are also mixing functions which mix the throttle and collective functions, and the throttle/collective and tail rotor functions. So you can know, it's very complicacy to set up both the helicopter and the radio!