Click the screen share button at the tool bar below
Select Share Screen
Check if users want to share the audio from Meetboard (usually if users are going to share a video with sounds, then it is suggest to enable), then choose the "Share screen" option
Allow Screen Share
Choose "start now" to allow Teams to share the screen of Meetboard
Complete
Now all the participants can see the screen share of Meetboard
Minimize
Users now can switch to other apps and exit Teams to let it runs in the background. The screen share process would still continue
Return to Meeting
Users can slide down from the top to notification shade and return to Teams meeting