Before you can create a Discord server, you need to create yourself Discord account. You can do this on Discord Website. If you already have the the account, just login.
Click the "+" button on the left-hand column.
A new window opens. Choose the option "Create My Own". Next you can choose the profile of your server "For a club or community" or "For me and my friends". Finally give your server a name.
In the bottom left, next to your user icon, you can find a cogwheel with the label User Settings. From there select Advanced. Switch on the Developer Mode.
Next, obtain the server ID for your server. Right click on top of your server icon (on left hand column.) From there choose copy ID.
Add this ID to `.env` file : GUILD_ID=your-discord-server-id.
Finally, obtain the invite link for your server. Right click on top of your server icon and choose Invite People. A new window opens. At the bottom, click Edit invite link
From the dropdown list for Expire after, choose Never. Press Generate a new link.
Add this ID to `.env` file : DISCORD_SERVER_INVITE=your-discord-server-invite.