assigning physical file to logical file.

How to configure application server file with logical file.( I don't have full idea about this . what I know is using /nfile tcode we assign logical file name to application server path and

using 'FILE_GET_NAME' function module, by supplying logical file we get the path of our application server

).

My lead doesn't have idea about this. How to convey him about logical file using which assiging physical file path. Can you explain clearly, so that I will work with my lead and get work done.

Your help will be appreciated highly