I suppose you could imagine entropy to be one who causes disorder so if they directed their power toward something it either get more disordered or less. More would mean like it would be melted without heat whereas less would mean it "unmelts" back to its original shape.
TIme would mean being able to move through it in either direction.
Space could mean being able to move through physical objects or it could mean expanding or shrinking an object even into a black hole but with possible dire consequences for doing it. It could also mean generating gravity waves.
Electromagnetism could mean they could act like a magnet and attract or repel a charged or magnetic susceptible article. Some of the consequences could be bad side-effects where in attracting a magnet, it might flip about as the poles try to align. Similarly, for charge one object might repel as expected but behind you another is attracted and now you must defend yourself to prevent from getting hit.
One problem for me here is that trying to align your gods to the physical laws too closely is going to severely limit your story ideas. It seems so much easier to imagine they all have these powers (and you can add more) but tend to use one power over the others perhaps because they got burned once when using the other powers incorrectly.
I imagine you could have a school where they are taught by their elders to use these powers.
Also Greek mythology stories with Zeus throwing lightning bolts... could be good models for your stories with respect to powers and their usage. One set of stories that approaches this theme is the Rick Riordan stories of modern day Greek mythology (Percy Jackson) playing out in the world today. Children of the Gods must battle ancient creatures in order to survive the petty nature of other Gods.
http://rickriordan.com/
My suggestion is that you should start with a short story patterned after some well known story theme and map it to your themes. Look for contests, where you could apply your skills and get to writing.
There's a cool book by Blake Snyder called "Saves the Cat" which while its for screen plays can be applied to short stories too. He breaks down movies into 10 categories of stories and then further breaks down these categories and illustrates what makes them work and what does not.
The book is basically a cookbook on how to write a story. Its still quite hard but he gives you a framework that is superior to anything you've ever learned in school.
There are numerous podcasts too that can give you insight into becoming an author. One is here:
https://writingexcuses.com/
You can find a lot of other ones via Google.
Lastly, there's the book by Ender's Game author, Orson Scott Card that gets into how to write sci-fi stories from his experience:
https://www.amazon.com/dp/1582976090/?tag=pfamazon01-20
Jedi
