Hello experienced DMs,

I am new to DMing, and I am creating a campaign for the first time as well. 

I want the main plot of my story to be about the queen angering a god, and said angry god is causing chaos among the kingdom, after killing the queen. The players will have to go to a far away kingdom in order to find a shrine of sorts to try to communicate with him and convince him to stop destroying their home. The god will get angry a this, and end up engaging in a battle with them. Eventually, they will beat him, and convince him to restore peace in the kingdom.

My main question is, how should I go about creating him? is that even something I can do, or should I just change the adventure to something easier to create? I need advice.

Thanks so much for your help :3

are you talking about a statblock, or lore?

lore, come up with whatever you want and give them some domains

stats, look at the aspects of bahumat and tiamat in the dragon book, those are the closest things to god statblocks that 5e has, and its not even a whole god

Empyrean, you can use that to give a God-like foe to face. Granted, in dnd lore empyreans are only children of God's and are likely not even close to the power of some, but still, that should work if you play it off well. And it would be quite a bit easier then throwing an unstoppable monstrocity at them, withought being too easy.

You’re getting a bit ahead of yourself; you’ve gone and created a railroad. 
It’s not up to you to decide how the PCs will solve the problem. And you definitely shouldn’t decide, before it happens, how the god would react. At that point, why are the players even there?

You’ve got an angry god wreaking vengeance. So far so good. You’ve got an option for how the PCs could contact the god. Also good. The problem is assuming they’ll take that option. Leave open the possibility that they’ll think of something else. And leave open the possibility they’ll find a way to convince the god to stop without fighting. Or, players being players, that they’ll ignore the god entirely and go chase something shiny they saw.

To answer your question, I’m not a fan of god battles. Gods aren’t started in this edition, because they shouldn’t be killable (imo). Rather than fight the god, I’d have them find some other way to stop it. Maybe it needs a sacrifice, maybe talking to it reasonably, maybe they credibly threaten something important to the god — a holy place, a high priest, a relic. That is, give them options for how they might overcome the god, and let them decide which to take. And be open to them coming up with something else entirely, so long as it works and is cool and fun for everyone.

To create a god, you just do it. There is no actual stat block for them, they just are. 

Being a new GM, what level would the party be when this adventure starts? It's unlikely that a low level party would face a god with any chance of success. If you're planning on having a high level party, what challenges will you put before them aside from the god being?

Foiling the gods plans or taking out their followers and or temples might be a good way to start.