I have two forms in my application. I used

Form2 frm = new Form2();

frm.Show();

to show the Second From.
How Can I populate the Data in datagrid in from 2 from Form1

in Vb
I can Write like
From2.text1.text = form1.text1.text

You could mark the controls as internal or public (they're protected by default), which would allow you to access them from other forms in your application. This can lead to a relatively brittle design changes to the form's implementation can break other code. (i.e. Changing a textbox to a dropdown list changes the method of access the content.) I would prefer to see a solution such as a property or method on Form2 that would allow you to access this data. For instance:

class Form2 : Form {
//...
  public string CompanyName {
    get {
      return tbCompanyName.Text;   // If implementation or field name ever changes, then change it once right here.
    }
  }
//...
}

In Form1:
form1.textBox1.Text = form2.CompanyName;