DRAINS uses many 'forms' with spaces allowing you to enter data for a component such as a pit or channel, or to review and change data that were entered previously.
They are opened by placing the mouse pointer on a component, clicking the right mouse button and choosing Edit Data from the menu that appears, e.g.:
You should place the pointer in the centre of the symbols for components that are located at one point, such as nodes, pits, detention basins, culverts, bridges and sub-catchments. For links such as pipes, channels and overflow routes, you can click on any point along their length. After some practise, you will be able to select particular components, even in complicated arrangements.