Preloader Help ~ ! ~

With my online portfolio im creating everything is fine but the “preloading”. What I am wondering is that i need a preloader script that will only load a certain amount of frames on scene 1, so say it will only load upto frame 18 and nothing more on that timeline in scene 1. Then frames from 18 onwards will have individual movie clips on them which will need to have a preloader on them each to load the content in that movieclip.

Can anyone help - iv read some tutorials but im stil confused…