Then you will need to update the "Newform.aspx" file for the current list.
You can add a "Custom List Form" by going to "Insert", "sharepoint controls", "custom list form.."
Choose your list name from the dropdown box and select "Add" radio button.
This will add the same form control to add a new list item for the particular list. You will be able to see the control layout with the table structure and you can update the description field to appear over the input field.
You can hide the other input control web part and once the form is working the way its supposed to, you can remove the original webpart.
I wanted to give you the link that can show the steps more graphically, however could not find one yet.
Will update the post with the link, if I have lost you anywhere.