How to have user input value

ok so I want a value to be inputed by the user in a text box so that

<PARAM NAME="USERNAME" ID="USERNAME" VALUE="user">

when I input Butterfly it should change into this:

<PARAM NAME="USERNAME" ID="USERNAME" VALUE="Butterfly">

How can I do this?


I am sorry I am a newbie programmer just taking my first semester of java and so I am not sure on how to make a user inputed value.

 

u can do this easily with javascript man.