CSS Styling in PHP echo

I am very new to using PHP and I am unsure how to style this table. I created a class but I am not sure if I make the changes in a separate CSS file because this did not work for me.

Do I use style tags? How can I do this?

//call function to get all the users or potential friends 
$friend_options = getUserForFriends();
//output of the options is in a table
print '<table class = "users"><form action="friends.php" method="post">';
print $friend_options;
print '</form></table>';


Just make sure the css file is linked in that php file. you can declare html doc under and link the css their