Our teacher explains nothing, he expects us to learn from reading the book.
I need help on how to start this assigment. I have attached the assigment.

Only one book?
Run as hell to the library and consult and study as many books you can about C++ functions. Then try and code ONE function and see if it works. Continue. Your teacher gave you sufficient info.

Do a little bit of research on how a for loop works. You use a for loop to repeat a set of commands until a condition is true / a fixed number of times. You can repeat the command of outputting an asterisk a specific number of times for each row ...

Oddly it is always the teacher's fault. Have you tried asking him/her for help? Better hurry your deadline is soon.