Any movie script ideas? please help!?

I am making a movie and have the responsibility of making the script. why? because i choose to. the movie is about some 14 year old kids named brad max zap and merritt. they find an underground city called ageya and have powers. they also fight a bad guy dark-sage called Maladar. i am at a writers block and bneed help at how they get there. please help!!!!!!!