how to add dynamic roles of location path in web config based on user input?

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C#

ASP.NET

WebConfig

how to add the role and location path to the web config to retrieve the value of a textbox based on user input?
ex: I have a textbox to add location path
I have a combobox (with items admin and user) to add roles.
ex: user input
location path = textbox
roles = combobox (items admin and user)
the save button,
when click the save button
the results go to the web config :

<location path="Report/ManageReport.aspx">
    <system.web>
      <authorization>
        <allow roles="ADMIN" />
        <deny users="*" />
      </authorization>
    </system.web>
  </location>