Suppose you want to apply 10% discount on all the products of category 1 .
Step 1 : Goto promotions tab and select catalog price rules .
Step 2 : Click on the Add New Rule on the top right side of grid.
Step 3 : Fill rule name, select status active & select customer groups .
Step 4 : Make a condition like below to apply discount .
Step 5 : Apply action like below and click Save and Apply button .
Step 5 : Enjoy discount on your store.
