Use the "Draw Bar" at the bottom of the screen to create something
Option 1: Select the usage (eg.
Residential) and start drawing an element of that type directly
Option 2: Draw a shape first hen add a usage later. Rectangle is just a convenient tool for drawing polygon's with right angles.
Select an element by left clicking.
A selected, active element is a red polygon.
Left click on nodes to delete them.
When dragging type in a number to drag an exact distance.
S to snap to features on map.
Right click on map features to create editable features from them.