If you have standard bezier selected (rotobezier unchecked) then you click and drag to pull out bezier handles. There is a lot of info in AE's help files on masking. Please look there for more details. The pen tool works the same way in AE as it does in Illustrator or Photoshop or just about any other vector drawing program. Here is a little video I made a long time ago that shows how to draw and animate a bezier path with the pen tool.
Goodness, what an awful tutorial.... Simply hold down the mouse while drawing to create bezier curves with tnagent handles instead of just straight segments...
after i create a curved path, the next place i click to make another point , the path to the next point is curved. how do i fix this?
This is basic stuff and it's basically the same way Illustrator or Photoshop works with bezier paths. You'll find a lot of helpful information if you just type masking or mask in the Search After Effects Help field at the top right corner of the app.
Directly from the Help Files: After Effects Help | Creating shapes and masks
Mylenium.. sorry you thought it was an awful tutorial. I made it in under a minute just to show this member the very basic task of creating a mask with the pen tool and animating the shape. I'll try and up the quality of my quick replies to simple operations.