Drag the selected operator from the Toolbox area and drop it onto the sheet.
The operator will appear on the sheet. You can then set its properties and connect it to another operator using a new data bus.
If you want to insert an operator between two existing operators connected by a data bus, drag the operator directly onto that bus. Only operators from the Middles group can be placed this way.
When you release the mouse button, the operator will be added to the data flow path.
The range of functional operators available when configuring a GRAVITY project is described in the 
Types and description of GRAVITY operators section.
Types and description of GRAVITY operators section.