File System simulation

Hey guys!!!
I know these simulations are too much but....
still another one and I am havin some problems with that///
I have to create a file system simulation that has to understand these commands:
cr a - create a new file named a, size ==0;
rm a - remove file a
op a - open file a
cl a - close file a
rd a - read file a
wr a - write file a
cp a b - copy file a to file b

I have to use:
DIRECTORY IMPLEMENTATITON
LINEAR LIST
ALLOCATION METHODS
CONTIGUOUS ALLOCATION
LINKED ALLOCATION(FAT)
FREE - SPACE MANAGEMENT
FREE-SPACE LIST
PROTECTION AND SECURITY

I HAVE TO USE AN ARRAY OF BYTES

P.S PLEASE GIVE ME SOME IDEA... I KNOW HOW TO DO SOME OF THE STAFF BUT I AM NOT SURE IF THIS IS THE RIGHT WAY TO APPROACH IT
LIKE INSTEAD OF ARRAY OF BYTES I WILL CREATE A BYTE BUFFER TO ALLOCATE THE SPACE...
BUT I HAVE NO IDEA HOW TO ALLOCATE THE SPACE ONCE THE FILE IS CREATED!!!!