New to Java

Sorry for posting again, but more people would see my post if it is new rather than old.

I am to write an application program to prompt the user for text and displays the frequency that each number appears in the text.

- I need to use a method to convery the entire text into lower-case prior to counting the letters.
- If the frequency count is 0, do not display it.


I am able to start to program and all, able to get the prompt and stuff, but how would I convert the letters of text into lower-case??