on the top of your carb you will se that the top of it can be unscrewed, unscrew that and pull it out......the slide is the bit the slides up and down in your carb.....if you take of your air filter and twist on your throttle and look in your carb you will see it moving.......sometimes the manufacture puts them in back to front.......therefore when you start your bike it will rev its tits off........just pull it out and spin it 180 degree and put it back in, it should sit nice and flush on the bottom of your carb with a small opening......the slide will only sit correctly if it is put back in the correct way
but i think its more to do with your idle screw so just play with that while your bike is going and your revs will slowly start to come down, you only have to turn the screw little bit by little bit........once your happy with your idle let it warm up properly and then fine tune ya idle because ya cant set your idle correctly when the engine is cold.