yes, its scary as hell.
quite a few sessions early on were horrible, just as you get the feeling of being up and away the ruddy thing just wants to go warp speed, and the natural thing to do is crouch down and lower the kite, normally with disastrous results.
all the advice above is of course correct, but just like many other vital steps in this crazy sport it just feels impossible at first.
you will get it quickly,
just one point of safety to remember,
at all costs don't run over your lines,
no matter how scary the situation, just avoid at all costs.
relax, go with it and stand up legs bent, bar out, kite slowly rising, keep board very low whilst trying to slow down, heading up or downwind.
practice S turns as soon as possible in gentle conditions, drop kite sizes as soon as possible.
after a while(many months) you will be looking for that warp speed feeling again, its fun when you can control it, but that takes lots of practice.