[modeller_usage] new to modeller

good day sir, pls i'm new to modeller and do not know where to start .i have read the manual but it get all confusing . i have not put in any input file cos i don't know where to start. i tried running the modeller  mod9v3 model-default.py and it gives me import site failed   cannot open file or directory . please help. if i can know the very first thing to do i think i can take it from there. thank you in advance chinwe