Not familiar with Fabric?

Best place to start is by going through 4-part tutorial

How to navigate the docs?

Here's a hierarchy of Fabric's object model, to make it easier:

Main rendering surface

• fabric.Canvas
• fabric.StaticCanvas

Things to fill objects with

• fabric.Color
• fabric.Gradient
• fabric.Pattern
• fabric.Shadow

2D shapes inheriting from fabric.Object

• fabric.Object
  • fabric.Line
  • fabric.Circle
  • fabric.Triangle
  • fabric.Ellipse
  • fabric.Rect
  • fabric.Polyline
  • fabric.Polygon
  • fabric.Group
  • fabric.Text
    • fabric.IText
  • fabric.Image
    • fabric.Image.filters
      • BaseFilter
      • Brightness
      • Convolute
      • GradientTransparency
      • Grayscale
      • Invert
      • Mask
      • Noise
      • Pixelate
      • RemoveWhite
      • Sepia
      • Sepia2
      • Tint
  • fabric.Path
    • fabric.PathGroup

2D entities NOT inheriting from fabric.Object

• fabric.Point
• fabric.Intersection

Main fabric namespace

• fabric
  • fabric.Observable
  • fabric.Collection

Fabric utilities and helpers

• fabric.util
  • fabric.util.object
  • fabric.util.array
  • fabric.util.string
  • fabric.util.ease

Fabric freedrawing brushes

• fabric.BaseBrush
  • fabric.PencilBrush
  • fabric.CircleBrush
  • fabric.SprayBrush
  • fabric.PatternBrush