Welcome to the World of JavaScript!!

<FORM NAME="LittleForm">
     <INPUT TYPE="text" NAME="yourname">
</FORM>

<SCRIPT>

var inputname = prompt("Please Enter your name: ", "Frank");

document.LittleForm.yourname.value = "Hi "+ inputname +"!!";
// OR document.LittleForm[0].value = "Hi "+ inputname +"!!";
// OR document.LittleForm.elements[0].value = "Hi "+ inputname +"!!";

document.write('<H2><CENTER><FONT COLOR="navy">');
document.write(inputname + ", try a variation of this page for yourself.");
document.write("</FONT></CENTER></H2>");

</SCRIPT>