Put yeast, 1 1/2 cups flour, sugar and salt into the bag. Add margarine and warm water. Press most of the air out of the bag and seal. Press and squeeze the bag with your hands until the dough becomes mixed. Open bag and add last 11/2 cups of flour. Seal the bag again and keep pressing and squeezing until the flour is worked into the dough. Add 1/4 to 1/2 cup more flour if your dough is very sticky. Unzip the bag and let the dough rest for 20 minutes. This will let the dough rise. Spray the pan with no-stick cooking spray. Squeeze the dough down. Then take the dough out of the bag and place it in the pan. Let the dough rest in the pan in a warm, but not hot, place to rise. The dough should double its size before baking. This will take about 1 hour. Preheat the oven to 375 F. Bake the bread for 25 30 minutes. Remove the bread from the pan to cool.