Go there, and you will see a couple of boards and RSS feeds. Then add other boards or feeds you want to subscribe to by pressing
esc on your keyboard.
There's nothing to download. Every change you make is stored locally in your browser.
If you want to create your own board, follow Robins instructions, but skip the first part about downloading the repository and starting a server. Instead, visit here to generate your keypair and continue from there.
Beware, though, I won't host the client forever and ever. Make sure to save backups of your keypair and Springfile for easy migration the day I decide to shut down. 😊