How can I avoid jagged edges? now it is last thing in my first project in blender. I made the model below in images and I thought everything is going well until I rendered it then I saw the quality is bad around the object that I built?
Is there any thing that I must do in render to have better result?
I will attach blender file to take a look.
Your compositing nodes are the cause. Because the blend does not have textures packed, I'm not 100% sure why you are compositing it the way you are.
However to fix the harsh edge around the container, simply check the Anti-Aliasing check box on both of the ID Mask nodes.


Here is what the mask looks like Anti-Aliased on the left, and without Anti-Aliasing (how you have it now) no the right.