You paste the coupon shortcode into the content area of any post, page, or custom post type where you want the coupon to appear.
Every coupon you create is given its own ID. To display one, drop its shortcode into the editor like this:
[coupon couponid="1"]
Replace 1 with the ID of the coupon you want to show. You can place the shortcode anywhere in the content, mix it with other text, and add more than one coupon to the same page.
The quickest way to insert it correctly is to use the Coupon Inserter button in the classic editor, or add a Coupon block in the block editor and pick your coupon from the list. Both build the shortcode for you so you do not have to remember the ID.
If you want a coupon in a sidebar or footer, see Displaying Coupons in a Sidebar or Text Widget. For a full walkthrough of building a coupon first, see Creating a Coupon and Displaying Coupons.