I apologize for this delayed reply to your gardening question and hope it is still helpful to you.
We at the gardening Q&A service can help with questions regarding plants but are not trained in helping with hardscapes. There are several good books on the topic available at most Home Depot garden centers and at other bookstores in your area. I did find the following web page which has a similar project that may be helpful to you:
And here's one more:
Thanks for the question. Best wishes for a wonderful gardening season. Please stop in again soon!
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