hey jolene.. am a league & school team bowler here as well. Im still improving (avg is around 180-190) but hope my advice helps... here goes..
I was a hook bowler in the first place but now converted to spinner.. but i guess u have to get ur basics right.
1st: steps, i willl encourage 5, gives u more time to prepare for ur release.
2nd: body posture, shoulders 90 degrees to ur swinging hand, do not "drop" ur shoulder when u release the ball.
3rd: extend out ur left hand during ur 3rd step, ur left hand is to balance urself when u swing out ur ball.
4th: the final step is the most important. its also called the power step (the sliding action). by the 4th step ur ball should be behind u, ready to be swung out, as u approach with ur 5th step, release ur ball and follow thru the movement. which means, swing ur hand up as well, with ur left hand still in balance.
the whole swinging of the ball is like a pendulum action. for the 1st-4th step as ur pulling back ur ball, try not to grip or force the ball tightly, feel the "pull" of ur hand by the ball. as u approach the final step, swing out with momentum n follow thru.
Methods on how aim. If ur a right hander try to stand at the first dot on ur right. the marking is on the ground. the spacing from 1 dot to another is 5 boards.. we will calculate on how many boards/dots to shift to get the desired result. for beginners its best to try and practice the basics by playing a straight ball. as u stand on the first dot u will release ur ball and aim towards the head pin.. if u do it correctly u can see the ball goes diagonally towards the centre. many pple have various methods to aim n u can always explore other methods.. haha. dis is just a guide for ya..
Hope this helps.. feel free to ask.. I believe there r many other experts who r willing to help u.
its very hard to explain in theory but u can go try it out. haha.