Here is my "little" problem:

- on submit page I have an input box
Code:
<input class="text3" type="text" name="dotpay_code" size="40" value="" />
When user submitting page he must enter a dotpay_code. After he submits a page I would like to insert that dotpay_code into custom_field named "code" - how can I do that - any ideas ?

Remember: the dotpay_code is available after submit button is pressed.