How can I read json file and bind it to gridview in ASP.NET, VB.NET

You'll need to break it down into tasks and solve each task. First you need to convert the JSON to some kind of memory structure like a DataTable or a list of objects, so google things like "vb.net deserialize json to datatable". Bear in mind that json can take any structure but a gridview has to be a table so the json you are reading needs to be suitable, if it isn't you'll need to manipulate it in some way to get it into a tabular form.

Once your data is in a datatable bind it to a gridview and learn how to use the gridview edit mode to add\remove\update rows.

Once you have that sorted you next need to convert the data in the gridview back to json so google how to serialize datatable to json.

If you're googling for how to bind json to a gridview, edit the gridview and save the gridview back all in a single article then you're never going to find it, you need to break things down to smaller tasks and tackle them in turn.

Check this post:
https://www.codeproject.com/Articles/1108006/From-zero-to-hero-in-JSON-with-Csharp