Creating dynamic form's textfield

Hi people,
I need to create a given number of textfields in a form. The number of textfields to be printed is set by the user in the same form.

I need to print a table with the given number of textfields in the middle of the form. So, the visitor enters the number of textfield and then press the "create custom form button", this button will call a js function that catches the value from the and prints the table with the textfields.

Thank you very much.

PD: Please excuse me, I know my english sux.