How do i make textarea user input a variable?

[phpnoob11]

Hello, i want to convert the user input of textarea into a varible that will then be used in a hidden input box... seeing as echoing it into the input box is the only way.. does anyone have any ideas on how to do this? thank you... im a very big noob so dont know much but dumb google didnt come up with anything at all when searching..

 

<div class="sf-box text">

 

<label for="fld<?php echo ++$forum_page['fld_count'] ?>"><span><?php echo $lang_profile['Yahoo'] ?></span></label><br />

<textarea  name="about_text" cols="45" rows="5">Please write about your self here.</textarea>

$about =$_GET[about_text]

 

<span class="fld-input"><input id="fld<?php echo $forum_page['fld_count'] ?>" type="text" name="form[yahoo]" value="<?php echo  $about ?>" size="70" maxlength="400" /></span>

</div>

 

is what i have at the moment not working at the moment, i just want it to be able to echo the text that was in textarea into the input field... and anyone know how to hide the input field too so there arent to boxes showing up? 

 

(i have tried using soley text area however i am having major problems with that and it aint working that way so this is the next best way because i think converting input box to textarea would cause to many conversion errors)

 

anyway please help

 

thank you