How To Create Transparent Orb In AI

[barrym67]

Hi There, did a bit of searching TG and Google, could not find the answer. How do I create a transparent vector orb in AI as per the attached sample. excluding the text - I just added that to show you what I need to do.

The text was placed behind the Orb, so you see there is more transparency in the centre than on the outside edge.

Any help would be appreciated, thank you!
Barry