There are several drawings which can be used as concentrations and then meditations. Links to them are below.
Each section should take a while to work through. To get the greatest benefit, you may find it works best if you do not just read through them. Rather, work with each, and when you feel you are finished with it - to the degree that is needed - then go on to the next section. You can always go back when that too is appropriate.
Apple in 3 Degrees of Meditation
Preparation
Moving Meditation
1 Blade of Grass
Sound
1 good turn
Resting