itch.io

I have an artist friend that I'm planning on asking to make a cover for my game since I'm not that good at drawing, but other than that all of the game assets and code are going to be made by me.

On your project, to the right you have the "Devlog" tab where you can write and publish devlogs. If you upload using Butler I think you can also attach older versions of your game but I haven't gotten the chance to try that.

You have to make a game on the Jam's time frame, after (or before) that you have to set up an itch.io project on you dashboard to be able to submit your entry using the "Submit your project" button (your game has to be published and public first). After the submission period ends the rating period starts and everyone can play each other games and rate them based on the jam's categories. And for the cash prizes (if you're interseted in that) you'll have to read what each jam says.