1. Click the Pencil button 
on the left toolbox.
2. Choose one of 7 styles in type list and set the size, opacity and other option to paint.
3. Global Path: Connect with other path before you did this.
4. Random Color: use random color without the color you set.
Plain(Random Color): 
Sketchy(Single Color): 
Shaded(Single Color): 
Web(Single Color): 
Trail(Random Color): 
Ribbon(Random Color): 
Fur(Random Color): 