Here's a step-by-step guide for how to use the Untapped.gg Twitch Extension when streaming MTG Online:

1. Go to your Stream Manager page on Twitch and click on the 'Untapped.gg for MTGA' button on the right side of the screen.

2. Click on 'Enable Magic the Gathering: Online'

3. Paste your MTGO deck in the white box or load the deck file, and then hit 'Save'

4. You are done! Your MTGO decklist will be displayed to your viewers on top of your stream