To create a SQL-Server database use SSMS (SQL-Server Management Studio).
Store data automatically, look at using Entity Framework (Core 5 for targeting .NET 5) and reverse engineering the database table(s) followed by implementing INotifyPropertyChanged.
For editing an online database without using Azure, create a local application either web or desktop to make all changes to the online database.
To get an idea about reverse engineering see the following which is not web but will apply to web with some effort on you. It's based on NuGet package EntityFrameworkCore.VisualBasic.
So the above provides starters for working through your questions. I have not one code sample for the above, all my work is done in C# but do write code samples on GitHub and Microsoft pages.