The key to a soft, light texture in 100% whole wheat bread is to use a flour with a high enough protein content.  The protein found in flour is primarily in the wheat GLUTEN, and it is the gluten that produces the texture which makes a pleasing loaf.

You will want to use a whole wheat flour designed for yeast breads.  DO NOT use a flour labeled "pastry" flour, as these are much lower in protein.  Look for labels such as "Bread Flour" or simply "Whole Wheat Flour".  Looking at the nutritional information, you will want your flour to have at least 4-5 grams of protein per 1/4 cup of flour.

Using Vital Wheat Gluten in your bread baking is one way to ensure that your bread dough will have enough gluten to form the texture you are working so hard to create.  Vital Wheat Gluten (NOT to be confused with GLUTEN FLOUR!) can be found via mail order or in most health food stores and specialty grocery stores.

While this item is optional, for beginners, I would definitely recommend using 2 Tablespoons per loaf.

Below are pictures of two brands of Vital Wheat Gluten.