You can dry your bread cubes two ways:

• Place your bread cubes in a large bowl and them them sit on the counter covered for 1-2 days to dry out. Stir the bread cubes every once in a while.
• If you don't have time to air-dry your bread, you can toast them. Lay bread cubes on large baking sheets in a single layer and toast at 250 degrees for 45-60 minutes stirring every once in a while. Transfer bread cubes to a large bowl.
• Preheat oven to 350 degrees and spray a 9x13 casserole dish with cooking spray. 
• In a skillet, melt butter and add the onion and celery. Saute until vegetables are soft. Pour mixture into the bowl with the bread. Add the parsley, sage, rosemary, thyme, salt, and pepper. Stir together. 
• In a medium bowl, whisk the eggs. Add the chicken broth and whisk together. Pour mixture over dry bread cubes and mix well. Pour into prepared baking dish. Cover with foil and bake for 35 minutes. Remove foil and bake for another 10-15 minutes until top is golden brown and middle is set. Note: At this point I sometimes drizzle a little extra butter on top with a sprinkle of salt. It makes all the flavors pop.