Hi level diagarms

hi all,

i am using asp.net and i am making a small student record system application.
with table name student, module, program of study and so on.

i am using n-tier architecture with layer PL,Service Layer, BLL and DAL.

i donot under stand that how i can make the high-level logical and physical architecture diagram of student record system using layers.
means what are the key components of my Student record System on each layer.
mean wht are the key componets of presentation layer, service layer, busness logic layer and DAL Layer.

any help to make the high-level logical and physical architecture showing key components on each layer will be highly appericated.

thanks
Ayesha