Need custom fields for Purchase Order and UPS/FEDEX Collect Account# on checkout page

I need for the customer to enter a Purchase order # and UPS/FEDEX Collect Account# during checkout.

I understand you can create a field in customer profile sign up etc but the customers always put
PO #'s in NOTES, I would prefer to add a separate field on the checkout page for PO # and UPS/FEDEX Collect Account#

So why the custom profile field does not suit you?

as stated i want customer to enter PO or Collect info at the CART page or checkout page. Custom field is for Users info during signup so customers are putting PO,UPS FEDEX Acct info in NOTES . I would like a specific field in the CART or CHECKOUT page since PO’s change per order.

But you can add profile fields to checkout as well