This article assumes you have started creating a new promotion using the "Create promotion" option on the Home page. This opens the "Create promotion" wizard.

The  wizard simplifies the task of setting up a new promotion greatly.
Just follow these steps:

The internal name of your promotion. Never displayed to visitors of your store.

Pick something that will help you identify this promotion in the list. 

Example: Retargeting offer for Facebook

There are two types of discount promotions you can build with Discount Ninja:

Enable or disable the following features for each promotion:

Select which products will participate in the promotion. You can select products based on collections, vendors, tags...

Select a fixed discount code or allow Discount Ninja to generate unique discount codes for each visitor that clicks "Apply discount".

Pick your preferred theme. In the next step you'll get a chance to customize the image, text, colors, ...

This steps shows validation errors if any. If there are no errors go ahead and click the "Create" button.

Click the "Test Discount Ninja" button to test your promotion. If you selected "Require Discount Ninja" you'll notice that the URL in the address bar contains a "token=ABCDE" component. This is what allows Discount Ninja to do its magic.
If necessary, browse to the page(s) of the participating products.

Click the copy button next to the URL to copy it to your clipboard. You can now paste it into an email, Facebook message... to share your promotion with your audience.

Best of luck!