Rocio,
There are many, many factors involved in making bread. If you're wanting to change the recipe... size, shape, quantity.... since you're a beginner, I suggest you find recipes that are written to suit your needs. For instance, if you're wanting rolls or smaller portions, find recipes that are written for those results, etc.
The type of yeast you use, the temperature and humidity during rising can affect the number of holes and texture of the bread, etc. Dividing the dough may result in the oven temp and time being too much. Try making different recipes by following them precisely to gain experience and then you'll get a feel for how things should work. Only when you have more experience would I advise altering recipes.
If you're truly interested in trying other bread recipes, look for
The Complete Book of Bread by Bernard Clayton, Jr. and
Nancy Silverton's Breads from the La Brea Bakery : Recipes for the Connoisseur by Nancy Silverton.
http://www.amazon.com/exec/obidos/tg...l/-/0679409076 http://www.amazon.com/exec/obidos/tg...l/-/068481174X