Re: How to add text to my adwords picture? Say a coupon code.
Is this for a display network campaign or for PLA's?
For a display network campaign, you might be able to use a sitelink extension. Sitelinks are now required to point to a different page than the ad landing page with enhanced campaigns, so this might be tricky. You could make up a coupon page, explaining the terms of the coupon and providing a link to the intended landing page. But that could reduce your conversion rate because of the extra link. Or you could include the text in your ad image.
For PLA's, you can add promotional text like this in the ad group that serves the PLA's.
Best of Luck!