what is a non-alphanumeric character
Alpha stands for alphabets and numeric stands for number. So a non alpha numeric character will be any symbol without letters (alphabets) or numbers. As you are aware, an upper case means capital letter. e.g., A, B, C, etc. and a lower case are small letters: a, b, c, etc. So out of the 8 number of characters, you were asked to use at least. one capital letter.