How to use left mouse button click in drag and drop inventory 4.10

I am using the drag and drop from the Wes Bunn training video. what i am trying to be able to do is use items from the inventory slots by right clicking and have a couple of buttons pop up to be able to use as different objectives. ( like : use , craft , etc…) or just be able to get a left mouse click on it to use the item. any help would be great.

also every time i right click twice my character falls though the floor. still can’t figure out that as well…