This video explains some of the changes in version 1.7 of the R.U.B.E Box2D editor.
See these links for tutorials on using the editor:
The workspace
Documents and views
Edit modes, selecting, and the cursor
Panels: Items, properties, script
Basic manipulation: translation, rotation, scaling
Editing bodies
Editing fixtures
Editing vertices
Editing joints
Revolute joints
Distance and rope joints
Wheel joints
Prismatic joints
Editing images
Script logs
The action menu
Custom properties