title: $_POST check against 'First Name' and security
body: <p>So, I know how to check for empty fields and whatever else. 
  I can't seem to figure out how to check for empty field, letters only, and make sure the default value from input is not being passed in a clean code.</p>
  
  <p>I tried using the switch but became confused when it came to checking for empty.</p>
  
  <p>Also, I used CSS to capitalize the disappearing default in the forms, so do I need to check with case sensitivity in mind? </p>