Wordpress Woocommerce Coupon Redeem Form & Woocommerce error fix

We need you to implement a coupon redeem form. This form should allow customers to put in their coupon code which will then add the appropriate coupon item to their cart and take them to the checkout page. The code for this is outlined here: [login to view URL] You will also fix the following errors on our wordpress website: (they occur on some page loads and when creating or editing woocommerce products). Warning: Cannot modify header information - headers already sent by (output started at /home/hopboxco/public_html/home/wp-content/themes/salient-child/[login to view URL]) in /home/hopboxco/public_html/home/wp-admin/[login to view URL] on line 197 Warning: Cannot modify header information - headers already sent by (output started at /home/hopboxco/public_html/home/wp-content/themes/salient-child/[login to view URL]) in /home/hopboxco/public_html/home/wp-admin/[login to view URL] on line 197 There is other Woocommerce work available once these two items are completed.