Do you have a radio all connected up and is the sim registering that its actually working?
If so you need to go to 'calibrate' and follow the prompts.
Next:
channel assignments
channel 1 is aileron/roll
channel 2 is elevator/pitch
channel 3 is throttle/power
Channel 4 is rudder/tail rotor
the other channel you need is the collective pitch...FMS call this some crazy name like hop or some dumb name...but this needs assigning tp channel 3.
You are aiming for 'mode 2' which means the right stick is cyclic...push forwards to go forwards and push right to go right and so on....the left stick up and down is heli up and down and left/right is the nose left right of the heli. sounds like you got that bit right.
Some people dont like FMS but I think it does a good enough job...I used it for ages...sure did me good
Rob