C programming help please (not c++)

I was given this question to write a program for and I don't understand nested loops. Can someone please show me what the code is supposed to look like so I can try to better understand it?

The program reads an unknown number of words strings that are only lowercase letters stopping when the word quit is entered. None of your strings will ever have more than 20 characters. The program counts the number of times that each vowel is seen, and prints the total number of occurrences of each vowel at the end. Using the input: the quick brown fox jumps over the lazy old dog quit The program should generate five lines of output in the format shown below: The vowel a occurred 1 times The vowel e occurred 3 times The vowel i occurred 1 times The vowel o occurred 5 times The vowel u occurred 2 times Hint: this program uses nested loops, the outer loop reads and processes a string, the inner loop iterates over each character in the string identifying/counting the vowels in that one string.