Aoe potion with drag and drop?

Hi, currently I am working on a game project and to showcase in my school next month. I'm kinda stuck with a lot of things but 1 thing that makes my brain died is the drag and drop. So, in the gameplay scene, there is a healing potion icon. The purpose of it is to hold the potion icon and drag and drop it onto the field, then it will show a healing circle indicator where the character will heal when you are inside the circle. Problem is, I do not know how to do it.

I look up the forum and mostly said use projector for the healing circle. As for drag and drop I really have no idea... May I have some coding suggestion? I know its rude to ask people to do my work but all I need is a kick-start on the scripts. C# scripts of course.

Thank you.