Answer: Good luck with your project! If you have a specific question please feel free to use the Q&A with one question per entry. As your next step I would strongly suggest you work with your county extension to run some basic soil tests and then based on the results begin adding any needed amendments for a flower bed.
In all likelihood your soil will benefit from adding organic matter. Autumn leaves as well as (herbicide free) grass clippings are great to use in the fall. You can add them to a compost pile or you can dig them into the soil to begin to break down during the winter. You could also consider planting a cover crop such as annual rye to protect your soil from erosion this winter.
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