How do I join this points together on a curves?
Select two nodes and press the F key. For the final pair, Fkey would give you a “can’t make segment” warning. Use the C key to close the curve.
can I hide the bezier curve’s contral point? and how do I extrude the face out? or do I need to convet it in to mesh? How do I do that also?
H key doesn’t work with curve nodes, afaik. To be able to move the control points in 3d space (curves are 2d by default) you have to have the 3d button activated, too. This is the one beside the back and front buttons on the Curve and Surface panel. One drawback is that you now have an unfilled shape. You can’t extrude faces from edges of the curve. You’d have to convert to mesh first. Tab back to object mode and press Alt C. One other thing to do after converting curves to mesh is to go to edit mode, select all vertices (A key) then W key, Remove doubles. Follow this with a Ctrl N to recalculate normals. It’s a good habit to have (Removing doubles and recalculating normals).