How to set the console?

I build a simple system with a VGA screen and a uart port. I follow the chapter of wiki, console on framebuffer (NEEK), to drive the VGA and it works.

Now I want to input from the uart and display in the screen. For example, input "ls" from the uart and list the folders tree in screen. But I don't know how to achieve it. Could somebody tell me how to achieve it? Or is there any document about it?

Thanks a lot.