For example, a curve similar to the one below on a Falloff would result in the 'Strength' of the Behaviour it is connected to resulting in a smooth transition from 'on' to 'off' (and back again) as it passed over a Shape's position.
Adjusting the graph is very similar to working with animation curves in the Graph Editor.
click + drag on a point to move it.
alt + click on a point to toggle the interpolation from linear to bezier.
click + drag to move a handle.
double click anywhere in the window to add a new point.
select > delete to remove a point.
There are several preset curves along the right hand side.
You can flip the graph horizontally and/or vertically using the button in the bottom right.
You can also manually input values using the input boxes at the bottom.
Turn on Grid Snapping using the button to the right of the inputs.
You can animate or make connections to points and handles here too! Just select a point or handle and then either keyframe or drag a connection to/from the
P (position) or
V (value) inputs.