[Help] On How to Auto Pops Out Textbox Wen A Particular Drop Down Menu is Selected In an Html form tag

Pls, to all in General, I nid a Simple Javascript func or code that Can Pops Up a text box if a particular option is selected in a drop down menu of an html form tag..
I.e
How Do you Want Us to Reach You?
Via:
<select name='contact'><option value='SMS'>SMS</option><option value='Email'>Email</option><option value='Web'>Web</option></select>

So, i want a textbox to be pops out individualy for evry selected option

ie <input type="text" name="sms"> to b Pops out if dem select sms method

<input type="text" name="email"> to b Pops out if dem select email method
and
<input type="text" name="web">
to b Pops out if dem select web method

thanks yet... Any Help rendered would b appreciated!