To open the Operations & Analysis Tool panel (A&O), either click the gear icon on the top right corner of the workspace above the open Layers panel OR click MENU then the double gear icon with O&A noted.
To open the layers panel should it not be visible, click the perforated design on the far right side of your screen where you see 'Layers'
Choose the link choice which you would like to work with (Presently Draw - Circle - At Point)
Follow the instructions presented on the left side and set a Title if desired, the Latitiude and Longitude for the starting center of the circle and the radius you would like it to be.
***Note : If the circle needs to be smooth, uncheck the 'accuracy' checkbox as long as it isn't large
Once the circle is created, you will see a confirmation. Click OK and then 'X' out of the A&O popup.
Your results will show on your map.