To create a Control rig, you must first have a characterized character. The Control rig is created based on the structure of the character.
The Character settings for the selected character display in the Navigator window.
IK effectors let you intuitively manipulate a character using a setup that simulates how a human body reacts when moving, and the FK effectors let you selectively fine-tune individual body parts. If you plan to do any fine-tuning, you should create a rig with both FK and IK effectors.
When using an IK only Control rig, all features associated with the FK rig are not present. For example, in the Character Controls window, the IK Blend T and IK Blend R sliders are not available. The Control rig constantly reaches towards the IK rig.
If the current character already has one or more Control rigs, a dialog box appears confirming that you want to create an additional Control rig. You can click Create New Rig to add an additional Control rig.
All Control rigs you create are added to the Control Rig section of the Scene browser. Each additional Control rig is named Control rig plus a sequential number.
By default, the small yellow effectors are FK, and the larger blue and red effectors are IK. You can customize the look of your Control rig effectors using the Properties window.