ok for starters your directional light needs to be MOVEABLE.
Lets start with the light you are using as your SUN as an example. Place it in your level if there is already not one and then in the Details tab under MOBILITY change that to MOVEABLE.
The in your LEVEL BLUEPRINT drag the light in. From here you are on the right path and there a few different ways to do what you want and also how you want to see the effect.
Anyways start here and if you need more help I will be happy to help if someone else doesn’t jump in before I check on here again.