Finance internship final report

I need help writing my final report for my internship in a financial department within the ministry of defense. It's hard to provide any information about the institute as it's a governmental body but I would like help with the following:

1- a description of general but detailed financial tasks ( what you would do in as accountant or in the payroll department etc..) 

2- a description of how the financial department operates in general

3- lessons learnt as a financial trainee

has to be 1500 words. This is extremely important so please take your time in understanding what I need