Since this bot uses Node.JS you will need to download and install Node.JS from the official Node.JS website.
To create a bot go to the Discord Developer Portal and then click the New Application button at the top right.
Once Discord asks for the application name type in whatever you want the name to be and then accept the Developer ToS agreement.
After clicking Create Discord should take you to the application page, at the middle left click Bot and then click Add Bot, Discord will ask if you're sure, click Yes, do it!.
To do this you'll need to click OAuth2 at the middle left of the page.
Once you're at the OAuth2 page, under Scopes check bot and applications.commands. You should now see a big Bot Permissions box at the bottom of the Scopes box, under the Bot Permissions box you'll want to check Read Messages/View Channels, Send Messages and Mention Everyone.
You should then see Generated URL at the bottom of the Bot Permissions box, click Copy and then paste the URL in a new tab.
On Add To Server select the server you want to add it to then click Continue. Afterwards Discord will show you the permissions you've given the bot, click Authorise.
Now close the tab and then go back to the applications Developer Portal, you'll need to go back to it to get the bot token.
If you're still on the OAuth2 page click the Bot tab at the middle left.
Click Reset Token and then copy the new long text. You may need to go through 2FA if you have 2FA enabled.
Now that you have the token you can go to the data folder and then open config.json in Notepad, Kate, or whichever text editor you use.
Once config.json opens up, replace ENTER_BOT_TOKEN with the bot token you copied from Discord and then save the file.
Open command prompt, konsole, or whichever terminal application you use in the root folder (root folder = folder that contains the index.js file) and then type npm i, this will install packages. Once the packages have installed type node index.js.
If everything goes well, you should see Connected to <bot_tag> in your terminal.
Now you can go to the server you added the bot to and then type /set_announcement_channel #channel to setup an announcement channel.
This bot uses JSON files to store announcement channel data, if you'd like to use something such as MongoDB, look into setting up an npm package such as Mongoose.
Since this is designed to be used in small/private servers I decided not to use Mongoose since it'd require more setup on the users side.
If you do plan on using this on many servers I highly recommend looking into proper databases, JSON files aren't designed to handle a lot of read and write operations and may corrupt.