A Discord ID looks like an 18-19 digit number (e.g., 646059759296053250). To get it, you need to:

1. Open User Settings (the gear icon next to your nickname in the bottom left)
2. Go to the section:
   • on desktop — Developer Mode
   • on mobile — Advanced
3. Enable Developer Mode
4. Click on your avatar in the bottom left
5. In the profile menu, click "Copy User ID"
6. Paste the copied ID into the field below