If you are not sure how to sit and how to breathe — these instructions (one page) from the Zen Mountain Monastery in upstate New York are very clear and complete. The photos are helpful too.
If you are searching for a cushion, check these two sites: DharmaCrafts and Samadhi Cushions. I have sat on cushions from both places, and the quality is nice. But you don’t need to buy anything. You can sit on an old phone book, if that works for you.
From an essay by Thanissaro Bhikkhu:
The two most important points in the Buddha’s teaching on karma — the two that set it apart from every other version of karma taught in his time — are that karma is intention, and that present experience is shaped by two kinds of intentions: past and present. Past intentions that are ready to ripen establish the range of possibilities that you could experience right now. Your present intentions pick and choose from those possibilities to shape what you actually experience. …
As you meditate, these points alert you to the fact that some things you experience in the present come from past intentions, and some from present intentions; you have to be able to tell the difference between the two if you want to read the results of your present actions.
Found at The Worst Horse.
From the Atlanta Journal-Constitution, Oct. 18, 2008:
Zen Buddhist meditation may help treat depression, attention-deficit disorder and anxiety, among other maladies, according to a recent study by Emory University neuroscientists.
Quoted at The Buddhist Channel.
Here is the research article: “Thinking about Not-Thinking”: Neural Correlates of Conceptual Processing during Zen Meditation. PLoS ONE 3(9): e3083 doi:10.1371/journal.pone.0003083