How I can I train with just a chessboard?

Is that like a printed-out kindle?

I think it's one of those weird things that monks used to draw pictures on.

Jordan, you asked a legitimate question, so I will give you a legitiamate answer. :D. 

You can improve/practice chess with just a board and pieces by doing micro-tactic chess drills.

http://www.masschess.org/Chess_Horizons/Articles/2001-01_Sample_400_Points_Part_1.pdf

Some of these are described in step 1 of this process, and once you get the hang of it only need to be done with a board and pieces.

How I can I train with just a chessboard?

It depends of the size of the chessboard

I ceased being interested the moment I saw "400 Points in 400 Days."

Perhaps practice end game variations. Mate yourself with different sets of pieces.

Better yet, find a book and do something useful and productive with your time.