With the 2 panels in Store Commander called Multi-Product Combinations and Specific Prices, you're gonna be able to setup a promotional offer only on Red product attributes of your shop!
First display all products using Catalog > Product List
If the display takes too long because of the high number of products, don't hesitate to create a simple view with Interface Customization tool - see related article below.
Then, select one product in the list and open the Multi-Product Combinations panel, Property column.
Select all products by clicking the icon on the product toolbar to take into account all products in the list.
Refresh the Multi-Product Combinations panel by clicking the icon . All combinations are now listed.
Now use the filtering tool of column 'Combination name' and enter 'red'. All combinations using the Red attribute are filtered.
Select one line and open the Specific Prices on the right handside.
Click the icon on the Multi-Product Combinations toolbar to take into account the entire list. of 'red' combinations.
In the Specific Prices panel, click to create the line. Enter the reduction, the start and the end date.
Finally, refresh the Specific Prices panel with .
You're done! All 'Red' products on your shops are now in promotion!
The steps in images: