About Entering Sketcher
You can enter Sketcher mode using these methods:
• Click > 
New. Under Type, select 
Sketch.
New. Under Type, select Sketch.• Open or create a new part and then click 
Sketch.
Sketch.• With a part open, select a tool and then click > . In the Sketch dialog box, set references and click Sketch.
You can also first select a sketch plane and then select a tool, bypassing the Sketch dialog box.