Please help on how to display certain functions on front page .

[jhakestylez]

I recently created function and upload it in oxygen as a plugin since i cant edit on oxygem theme functions.php, but the page is gone..

(the functions i uploaded as plugin)

/* 
Plugin name: helloworld
Author: Anonymous
Version: 1.0
Description: Outputs 

*/

 <?php
function writeMsg() {
  echo "Hello world!";
}
?>

then i made a code block on front end and write this code in php:

<?php
  echo writeMsg();
?>

anyone can help me, please?