There are two ways to create resources:
(i) drag-and-drop the result of a search, and, (ii) shift-click in the query creator (this will create a new variable).
There are two ways to create properties:
(i) drag-and-drop an existing property from the describe tool, and, (ii) press shift and drag one element to another.
To remove an element use right click to display more options and click in remove
The colour of the borders denotes the type of the elements:
Resources can be blue (constraints) or gree (variables).
Properties can be orange (object properties), purple (datatype properties) or red (variable properties).
There are two property types:
(i) Object type properties are properties that links two resources, and, (ii) Datatype properties are properties that stored literal information (strings, numbers and so on), this kind of data can not be stored as a resource and can not have properties.