Using the Duet Web Control interface, be sure you are on the Machine Control tab by simply clicking Machine Control in the middle right of the interface. Once you are on the Machine Control tab, you will see on the left side of the screen a section called User-Defined Macros. There you will see a series of drop down menus in blue. Select the Calibration macro drop down, then select Manual Bed Leveling to begin the Manual Bed Leveling sequence.