how to get the value of DatagridView and transfer data in forms?

When you have bound your DataGridView to an Object you can pass the bound Object to another form like this (answer copied from a question I answered a while back):
Here is the original question: How to pass the Value one form to another form in windows form[^]

To pass Objects between Forms you can follow one of these approaches:
One is using a Property on one of your Forms.

MyForm frm = new MyForm();
// It is possible to set MyValue at any point in your code, as long as you have a reference to an instance of MyForm.
frm.MyValue = "some value";
frm.Show();

Another is passing it to the constructor.

public partial class MyForm : Form
{
   private String _myValue;
   public Form1(String myValue)
   {
      InitializeComponent();
      _myValue = myValue;
      // Possibly use myValue here.
   }
   // Do stuff with _myValue here.
}

Usage would look like this:

MyForm frm = new MyForm("some value");
frm.Show();

Another approach could be to use a Method...

public partial class MyForm : Form
{
   private String _myValue;
   public void SetValue(String myValue)
   {
      _myValue = myValue;
     // Possibly do stuff with myValue here.
   }
   // Or use _myValue here.
}

Usage:

MyForm frm = new MyForm();
frm.Show();
// Once again, you can use this anywhere in your code, as long as you have a reference to the instance of MyForm.
frm.SetValue("some value");

So now you got your data in another Form, all you need to do is handle it there, edit it etc. and update it in the Form it originally came from.
You can also do this with unbound data, except the updating of your original grid might be some extra work.

The code is in C#, but any convertor[^] can convert it to VB for you :)

Hope it helps :)