Choosing a wine that complements a meal
That's a ridiculously huge question. So huge that you'd need a whole book to answer it! Fortunately, that book has been written:

  

What to Drink With What You Eat
The Definitive Guide to Pairing Food with Wine, Beer, Spirits, Coffee, Tea —  Even Water — Based on Expert Advice from America's Best Sommeliers.
by Andrew Dornenburg and Karen Page 

If you really want to understand this issue, this is by far the best answer. Worth every penny.