How do i share my screen

I having difficulty sharing my screen. I press share screen and not sure what should happen next? it says it cant be shared?
i have documents on my word to share a presentation have no clue what to do. Please someone with patience help me.

i need to find a help button but there doesnt seem to be one.

Which browser are you using?

other than that here is how you do it: How to share your screen on Jitsi - Hardlimit