Step 1: Login to your Amazon Advertising account from Kindle Direct Publishing
Step 2: Click on the "Create campaign" button
Step 3: Select Lockscreen Ads campaign type by clicking on the "Continue" button under the tile
Step 4:
Step 5: Add product to advertise
Step 6: Select category that is related to your book. You should be as granular as possible to have greater control later for optimizing the campaign
Step 7: Set default bid
Step 8: In this step you have a chance to be creative and add custom text to the ad.
Step 9: Click on "Submit for review" so the campaigns can be audit by Amazon and start running.