Hi, Thanks for your question.
Here is an example based on a 10% Off discount.
First go to the Product > Sales menu. Click on Add new and enter the basic information requested (code, start date, end date, etc.)
Then click on the Required conditions tab. Here you will define the required conditions to apply the discount. For example the list of products that grants the promotion.
Make sure to FLAG the ACTIVE checkbox otherwise the discount wil not be active.
Choose the condition type : for example Products > SKUs and enter the list of SKUs. If you want the conditions to be categories, catalogs, brands, etc. it is also possible and you can enter multiple SKUs etc. at the same time
When you have defined the condition, click on the "Discount granted" tab :
Select the discount type (percentage off) for example and then the percentage (10percent for instance).
Save your discount and wait for 3 minutes (cache duration on promotions).
You can also refresh the cache instanntly : Administration > Application Tiers then entre the application tiers anc click on clear cache.
The promotion should apply --> check on your website, that it works as you want.